ORCID Profile
0000-0002-1086-5142
Current Organisations
Silpakorn University
,
Nederlands Studiecentrum Criminaliteit en Rechtshandhaving
,
KU Leuven
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Publisher: Wiley
Date: 26-07-2021
Abstract: Segmentation of organs and structures, as either targets or organs‐at‐risk, has a significant influence on the success of radiation therapy. Manual segmentation is a tedious and time‐consuming task for clinicians, and inter‐observer variability can affect the outcomes of radiation therapy. The recent hype over deep neural networks has added many powerful auto‐segmentation methods as variations of convolutional neural networks (CNN). This paper presents a descriptive review of the literature on deep learning techniques for segmentation in radiation therapy planning. The most common CNN architecture across the four clinical sub sites considered was U‐net, with the majority of deep learning segmentation articles focussed on head and neck normal tissue structures. The most common data sets were CT images from an inhouse source, along with some public data sets. N‐fold cross‐validation was commonly employed however, not all work separated training, test and validation data sets. This area of research is expanding rapidly. To facilitate comparisons of proposed methods and benchmarking, consistent use of appropriate metrics and independent validation should be carefully considered.
Publisher: MDPI AG
Date: 31-01-2023
DOI: 10.3390/PHARMACEUTICS15020467
Abstract: In this study, 3D-printed tablets with a constant surface area were designed and fabricated using polylactic acid (PLA) in the outer compartment and polyvinyl alcohol and felodipine (FDP) in the inner compartment. The influences of different surface geometries of the inner compartment, namely, round, hexagon, square, and triangle, on drug release from 3D-printed tablets were also studied. The morphology and porosity of the inner compartment were determined using scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy, respectively. Additionally, drug content and drug release were also evaluated. The results revealed that the round-shaped geometry seemed to have the greatest total surface area of the inner compartment, followed by square-shaped, hexagon-shaped, and triangle-shaped geometries. FDP-loaded 3D-printed tablets with triangle and hexagon surface geometries had the slowest drug release (about 80% within 24 h). In the round-shaped and square-shaped 3D-printed tablets, complete drug release was observed within 12 h. Furthermore, the drug release from triangle-shaped 3D-printed tablets with double the volume of the inner compartment was faster than that of a smaller volume. This was due to the fact that a larger tablet volume increased the surface area contacting the medium, resulting in a faster drug release. The findings indicated that the surface geometry of 3D-printed tablets with a constant surface area affected drug release. This study suggests that 3D printing technology may be used to develop oral solid dosage forms suitable for customized therapeutic treatments.
Publisher: Elsevier BV
Date: 1998
Publisher: Elsevier BV
Date: 02-2022
DOI: 10.1016/J.MRI.2021.10.012
Abstract: Automated brain tumour segmentation from post-operative images is a clinically relevant yet challenging problem. In this study, an automated method for segmenting brain tumour into its subregions has been developed. The dataset consists of multimodal post-operative brain scans (T1 MRI, post-Gadolinium T1 MRI, and T2-FLAIR images) of 15 patients who were treated with post-operative radiation therapy, along with manual annotations of their tumour subregions. A 3D densely-connected U-net was developed for segmentation of brain tumour regions and extensive experiments were conducted to enhance model accuracy. A model was initially developed using the publicly available BraTS dataset consisting of pre-operative brain scans. This model achieved Dice Scores of 0.90, 0.83 and 0.78 for predicting whole tumour, tumour core, and enhancing tumour subregions when tested on BraTS20 blind validation dataset. The acquired knowledge from BraTS was then transferred to the local dataset. For augmentation purpose, the local dataset was registered to a dataset of MRI brain scans of healthy subjects. To improve the robustness of the model and enhance its accuracy, ensemble learning was used to combine the outputs of all the trained models. Even though the size of the dataset is very small, the final model can segment brain tumours with a high Dice Score of 0.83, 0.77 and 0.60 for whole tumour, tumour core and enhancing core respectively.
Publisher: Elsevier BV
Date: 02-2008
DOI: 10.1016/J.JCONREL.2007.10.023
Abstract: Self-assembling pectin-liposome nanocomplexes (PLNs) were prepared by a simple mixing of cationic liposomes with pectin solution, in order to improve intestinal absorption of calcitonin (eCT). Both in-vitro and in-vivo evaluations for PLNs were evaluated. The results showed that average particle size of PLNs was significantly larger than that of initial cationic liposomes. The surface charges were shifted from positive to negative after mixing with pectin. The PLNs made of high degree of esterification (DE) pectin showed less negatively charged values than those made of low DE pectin. The entrapment efficiency in cationic liposomes was in the same range even if the drug loading was increased. The in-vivo mucoadhesive test of pectin by confocal laser scanning microscopy demonstrated stronger mucoadhesive properties of PLNs made of low DE pectin, compared to cationic liposomes and PLNs made of other pectins. Moreover, high intensities of a fluorescent marker could be observed throughout the small intestines (i.e. duodenum, jejunum and ileum) and remained at the site of mucoadhesion even after 6 h of administration of PLNs made of low DE pectin. The eCT-loaded PLNs demonstrated a strong pharmacological action over the eCT solution and eCT-loaded liposomes, in which an enhanced and prolonged reduction in plasma calcium concentration of rats was observed. This was attributed to the ability of pectin to adhere to the mucus layer and prolong retention in the intestinal mucosa.
Publisher: Trans Tech Publications, Ltd.
Date: 12-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.1060.37
Abstract: The low solubility of poorly water-soluble drug is a major problem of oral drug adsorption. The self-emulsifying system can be applied to eliminate the drug dissolution step and improve the drug absorption. In this research, liquid self-nanoemulsifying drug delivery system (SNEDDS) composing of polyethoxylated castor oil, caprylic/capric glyceride and diethylene glycol monoethyl ether was developed. The drugs with similar structure but different lipophilicity (log P ), nifedipine (NDP), felodipine (FDP) and manidipine (MDP), were investigated. Size and size distribution of emulsion after dilution in acid medium and in vitro drug dissolution were determined. The results showed that the size of emulsions obtained from dilution of SNEDDS in acidic medium ranged from 100-150 nm. Drug dissolution from SNEDDS was different depending on lipophilicity of drug, i.e., 98.6, 74.3 and 52.5% for NDP (log P 2.50), FDP (log P 4.46) and MDP (log P 5.46), respectively. The results suggested that the difference in lipophilicity may influence the drug dissolution from SNEDDS.
Publisher: Elsevier BV
Date: 10-2006
DOI: 10.1016/J.IJPHARM.2006.05.045
Abstract: Hydrophilic gels, formed by the interaction of calcium ions with either sodium alginate or potassium pectinate, can be deposited as a wet coating on to the surface of drug loaded pellets. If the coated pellets are dried, they could be dispensed to a patient in a capsule for oral delivery of the active drug. In contact with the aqueous fluids of the gastrointestinal tract, the gel coat will rehydrate, swell and will sustain the release of active drug from the core. In order to facilitate the development and refinement of this novel coated system, it is beneficial to have a method that can produce free gel films in a manner that closely mimics the way the gel coat is formed and deposited on the pellet surface. Traditional film producing methods would involve the spraying or depositing (by evaporation) the gel forming polysaccharide on to an inert surface, drying it and then exposing the dry film to a solution containing calcium ions. Because the film is dry before it is gelled, it is fundamentally different to the wet gel coats that are deposited on to the pellets. We have developed a method to produce wet gel films and have evaluated different manufacturing conditions in order to optimize the quality of the completed gel film. Additionally, we have used these films to assess the effect that the type of polysaccharide and the environmental conditions experienced during rehydration (pH and ionic strength) has on the mechanical properties and the microscopic morphology of the gel. Irrespective of the rehydration medium, the calcium pectinate gel films were softer, weaker and more porous, than the calcium alginate films. Although calcium alginate gels that were rehydrated in 0.1M NaCl were porous, the same films rehydrated in either water, simulated gastric fluid USP (without pepsin) or 0.1M HCl were stronger and much more dense microscopically. Furthermore, of the four different alginates that were evaluated, those with a high content of guluronic acid saccharides were the strongest but most brittle when rehydrated in water.
Publisher: Elsevier BV
Date: 10-2012
DOI: 10.1016/J.EJPB.2012.07.010
Abstract: The purpose of this study was to improve in vitro dissolution and in vivo absorption of itraconazole (ITZ), a poorly water-soluble drug, by means of novel pectin-based nanoparticles prepared from nanoemulsion templates. Nanoemulsion templates were prepared by a high-pressure homogenization using pectin (i.e., 0.5-3.0%w/w low-methoxyl pectin (LMP), amidated low-methoxyl pectin (ALMP), or high-methoxyl pectin (HMP)) as an emulsifier and chloroform as an oil phase. HMP provided good oil-in-water emulsions with ITZ loaded in the oil phase. The chloroform in nanoemulsions was then removed to produce the suspensions of nanoparticles dispersed in water phase. After lyophilization, the dried core-shell nanoparticles with good properties in terms of redispersibility, dissolution, and stability were obtained. The alteration of ITZ crystallinity was clearly observed from powder X-ray diffractogram while no interaction between ITZ and pectin was found in the nanoparticles. The ITZ-loaded nanoparticles showed high percent drug dissolved, especially those prepared from HMP, and could maintain their good dissolution properties even after 6-month storage. The in vivo absorption study in fasted rats demonstrated that pectin-based nanoparticles prepared from nanoemulsion templates could improve absorption of ITZ, that is, 1.3-fold higher than the ITZ commercial product (p<0.05). Pectin type highly influenced the dissolution properties and also in vivo plasma profile. These findings suggested that HMP-based nanoparticles seem to be a promising formulation due to their high AUC(0-24h) and C(max).
Publisher: Elsevier BV
Date: 03-2019
Publisher: Trans Tech Publications, Ltd.
Date: 12-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.1060.33
Abstract: To avoid unpredictable time to float due to variable pH of the gastric fluid in each subject, sublimation technique is the new interesting approach to prepare non-effervescent floating drug delivery system (FDDS). In this study, a floating matrix tablet using borneol as sublimable agent was developed. The system consists of drug, matrix-forming polymer and sublimable agent. The highly porous and low-density floating matrix tablet was obtained when borneol was sublimated. The floating matrix tablets immediately floated and maintained buoyancy over 8 h. The sublimation of borneol increased with increasing sublimation temperature and incubation time. Increasing amount of sublimable agent exhibited lower density of the floating tablet because of higher porous structure. The results demonstrated that boneol was one of good candidates to be used as sublimable agent for non-effervescent floating tablets. However, physical properties of the matrix floating tablets were needed to be concerned.
Publisher: Wiley
Date: 25-09-2021
DOI: 10.1002/ACM2.13432
Abstract: To determine baseline accuracy and reproducibility of T 1 and T 2 relaxation times over 12 months on a dedicated radiotherapy MRI scanner. An International Society of Magnetic Resonance in Medicine/National Institute of Standards and Technology (ISMRM/NIST) System Phantom was scanned monthly on a 3T MRI scanner for 1 year. T 1 was measured using inversion recovery (T 1 ‐IR) and variable flip angle (T 1 ‐VFA) sequences and T 2 was measured using a multi‐echo spin echo (T 2 ‐SE) sequence. For each vial in the phantom, accuracy errors (%bias) were determined by the relative differences in measured T 1 and T 2 times compared to reference values. Reproducibility was measured by the coefficient of variation (CV) of T 1 and T 2 measurements across monthly scans. Accuracy and reproducibility were mainly assessed on vials with relaxation times expected to be in physiological ranges at 3T. A strong linear correlation between measured and reference relaxation times was found for all sequences tested ( R 2 0.997). Baseline bias (and CV[%]) for T 1 ‐IR, T 1 ‐VFA and T 2 ‐SE sequences were +2.0% (2.1), +6.5% (4.2), and +8.5% (1.9), respectively. The accuracy and reproducibility of T 1 and T 2 on the scanner were considered sufficient for the sequences tested. No longitudinal trends of variation were deduced, suggesting less frequent measurements are required following the establishment of baselines.
Publisher: Elsevier BV
Date: 05-2008
DOI: 10.1016/J.EJPB.2007.09.013
Abstract: Floating multi-layer coated tablets were designed based on gas formation. The system consists of a drug-containing core tablet coated with a protective layer (hydroxypropyl methylcellulose), a gas forming layer (sodium bicarbonate) and a gas-entrapped membrane, respectively. The mechanical properties of acrylic polymers (Eudragit RL 30D, RS 30D, NE 30D) and ethylcellulose were characterized by the puncture test in order to screen a suitable film for the system. Eudragit RL 30D was chosen as a gas-entrapped membrane due to its high flexibility and high water permeability. The obtained tablets enabled to float due to the CO2-gas formation and the gas entrapment by polymeric membrane. The effect of formulation variables on floating properties and drug release was investigated. The floating tablets using direct-compressed cores had shorter time to float and faster drug release than those using wet-granulated cores. The increased amount of a gas forming agent did not affect time to float but increased the drug release from the floating tablets while increasing coating level of gas-entrapped membrane increased time to float and slightly retarded drug release. Good floating properties and sustained drug release were achieved. These floating tablets seem to be a promising gastroretentive drug delivery system.
Publisher: Elsevier BV
Date: 2010
Publisher: Elsevier BV
Date: 05-2008
DOI: 10.1016/J.EJPB.2007.09.012
Abstract: Pellets containing microcrystalline cellulose (MCC), a model drug (theophylline) and a range of levels of sodium alginate (i.e., 10-50% w/w) were prepared by extrusion/spheronization. Two types of sodium alginate were evaluated with and without the addition of either calcium acetate or calcium carbonate (0, 0.3, 3 and 10% w/w). The effects of amount and type of sodium alginate and calcium salts on pellet properties, e.g., size, shape, morphology and drug release behavior, were investigated. Most pellet formulations resulted in pellets of a sufficient quality with respect to size, size distribution and shape. The results showed that the amounts of sodium alginate and calcium salts influenced the size and shape of the obtained pellets. However, different types of sodium alginate and calcium salt responded to modifications to a different extent. A cavity was observed in the pellet structure, as seen in the scanning electron micrographs, resulting from the forces involved in the spheronization process. Most of pellet formulations released about 75-85% drug within 60 min. Incorporation of calcium salts in the pellet formulations altered the drug release, depending on the solubility of the calcium salts used. The drug release data showed a good fit into both Higuchi and Korsmeyer-Peppas equations.
Publisher: Trans Tech Publications, Ltd.
Date: 12-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.1060.128
Abstract: The aim of study was to determine the effect of glycerol on the properties of tapioca starch films. The films containing various amounts of glycerol (0-30 %w/w) were prepared by casting method. Texture analyzer, x-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) were used to comparatively characterize the films. The result indicated that mechanical properties were depended on amount of incorporated glycerol. The films containing 0-10 %w/w of glycerol showed brittle characteristic while those containing 20-30 %w/w demonstrated elastic film, suggesting the plasticization effect of glycerol. As indicated by x-ray diffractometry, the crystallinity was increased as increasing percentage of glycerol. The 3D structural change after incorporation of glycerol in polymer chain of starch might affect the properties of films. However, the FTIR spectra did not show clear interaction between glycerol and starch. The physical entrapment of glycerol in amylose chain might be a possible explanation for the results.
Publisher: Elsevier BV
Date: 06-2011
Publisher: Elsevier BV
Date: 12-2021
Publisher: Trans Tech Publications, Ltd.
Date: 04-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.506.307
Abstract: Solid dispersions of poorly water-soluble drug, indomethacin (IMC), and carriers at a ratio of 1:9 were prepared by melting method. The carriers used in this study were polyethylene glycol 4000 (PEG4000), hydroxypropyl methylcellulose (HPMC) and pectin. The solid dispersions obtained were characterized by powder x-ray diffractometry (PXRD) and dissolution studies. PXRD patterns showed that all solid dispersions led to amorphous products while their physical mixture still showed the crystalline state of drug. Crystalline drug was clearly detectable in solid dispersion products containing only IMC and PEG4000 after storage for 2 months. The formulations with biopolymer (i.e., HPMC, pectin or their combination) showed no drug crystal after storage. More than 80% of IMC dissolved within 5 minutes for all formulations after preparation while less than 40% of IMC dissolved, within 5 minutes, from the formulations containing IMC, PEG4000 and HPMC after storage for 2 months. The slower drug dissolution may be due to the gel-forming properties of HPMC as well as the agglomeration of the products after storage. The results suggested that either HPMC or pectin in solid dispersions can help to prevent the crystallization of amorphous IMC in solid dispersion, probably by a polymer anti-plasticizing effect. Pectin showed superior stabilizing effect with no retardation effect on drug dissolution.
Publisher: Trans Tech Publications, Ltd.
Date: 04-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.506.429
Abstract: The objective of this study was to investigate the effect of coconut oil and different surfactants on stability of nanoemulsions that were prepared by simple homogenization (13,500 rpm, 10 minutes). Coconut oil, sunflower oil and castor oil at the concentration of 20-40% w/w were used as the oil phase. Polysorbate 20, polysorbate 80 and Cremophore RH40 were used as surfactant whereas sorbitan monooleate and polyethylene glycol 400 were used as co-surfactants. The formulations containing coconut oil in the range of 20-40% w/w and the ratio of polysorbate 80 to sorbitan monooleate of 2:1 and 3:1 provided nanosized emulsions (100-500 nm). The zeta potential values ranged from-41.51 to-16.97 mV. The prepared nanoemulsions were stable for at least 7 days at 8 °C. The temperature cycling test (storage at 4 °C for 24 hours and at 45 °C for 24 hours) was performed. It was found that the formulation containing 30% w/w of coconut oil, 22.5% w/w of polysorbate 80 and 7.5% w/w of sorbitan monooleate was stable for 1 cycle. The results indicated that a decrease in the concentration of surfactant and an increase in the concentration of oil affected the stability of nanoemulsions.
Publisher: Wiley
Date: 08-2021
Publisher: Elsevier BV
Date: 12-2016
Publisher: Elsevier BV
Date: 11-2008
Publisher: Elsevier BV
Date: 11-2008
Publisher: Elsevier BV
Date: 08-2007
DOI: 10.1016/J.EJPB.2006.12.014
Abstract: The aim of this study was to investigate swelling and erosion behaviors of hydrophilic matrix tablets using pectin and their impact on drug release. The matrix tablets were prepared by direct compression using different types of pectin. Swelling and erosion studies of pectin matrix tablets were carried out in various media. The pectin matrix tablets formed a continuous gel layer while in contact with the aqueous medium undergoing a combination of swelling and erosion. The swelling action of pectin matrices was controlled by the rate of its hydration in the medium. Release studies showed that the swelling and erosion of matrices influenced the drug release. The extent of matrix swelling, erosion and diffusion of drug determined the kinetics as well as mechanism of drug release from pectin-based matrix tablets. The release data showed a good fit into the power law or the Korsmeyer-Peppas equation indicating the combined effect of diffusion and erosion mechanisms of drug release.
Publisher: Elsevier BV
Date: 03-2012
DOI: 10.1016/J.LFS.2012.01.008
Abstract: Most of the conventional chemotherapeutic agents used against cancer have poor efficacy. An approach to improve the efficacy of cancer chemotherapy is the development of carrier systems that can be triggered to release the anticancer drug in response to extracellular or intracellular chemical stimuli. To this end, pH-responsive nanocarriers have been developed to target drugs either to the slightly acidic extracellular fluids of tumor tissue or, after endocytosis, to the endosomes or lysosomes within cancer cells. These systems can release the drug by specific processes after accumulation in tumor tissues via the enhanced permeability and retention (EPR) effect or they can release the drugs in endosomes or lysosomes by pH-controlled hydrolysis after they are taken up by the cell via the endocytic pathway. This strategy facilitates the specific delivery of the drug while reducing systemic side-effects with high potential for improving the efficacy of cancer chemotherapy.
Publisher: Springer Science and Business Media LLC
Date: 09-08-2021
Publisher: Elsevier BV
Date: 03-2022
Publisher: Elsevier BV
Date: 2011
Publisher: Springer Science and Business Media LLC
Date: 21-05-2021
Publisher: Wiley
Date: 02-05-2021
DOI: 10.1002/JMRS.469
Abstract: Stereotactic ablative body radiotherapy (SABR) is currently indicated for inoperable, early‐stage non‐small cell lung carcinoma (NSCLC). Advancements in image‐guidance technology continue to improve treatment precision and enable reductions in planning safety margins. We investigated the dosimetric benefits of margin reduction, its potential to extend SABR to more NSCLC patients and the factors influencing plan acceptability. This retrospective analysis included 61 patients (stage IA–IIIA) treated with conventional radiotherapy. Patients were ineligible for SABR due to tumour size or proximity to organs at risk (OAR). Using Pinnacle auto‐planning, three SABR plans were generated for each patient: a regular planning target volume margin plan, a reduced margin plan (gross tumour volume GTV+3 mm) and a non‐margin plan. Targets were planned to 48Gy/4 or 50Gy/5 fractions depending on location. Plans were compared in terms of target coverage, OAR doses and dosimetric acceptability based on local guidelines. Predictors of acceptability were investigated using logistic regression analysis. Compared to regular margin plans, both reduced margin and non‐margin plans resulted in significant reductions to almost all dose constraints. Dose conformity was significantly worse in non‐margin plans ( P 0.05) and strongly correlated with targets’ surface area/volume ratio ( R 2 = 0.9, P 0.05). 26% of reduced margin plans were acceptable, compared to 54% of non‐margin plans. GTV overlap with OARs significantly affected plan acceptability (OR 0.008, 95% CI 0.001–0.073). Margin reduction significantly reduced OAR doses enabling acceptable plans to be achieved for patients previously excluded from SABR. Indications for lung SABR may broaden as treatment accuracy continues to improve further work is needed to identify patients most likely to benefit.
Publisher: Elsevier BV
Date: 07-1999
DOI: 10.1016/S0928-0987(99)00010-X
Abstract: Pectin has been investigated for its ability to produce solid calcium pectinate gel (CPG) beads containing bovine serum albumin (BSA). Several factors can influence the properties and release characteristics of the CPG beads. In this study, the effect of calcium concentration, hardening agent and drying condition on the encapsulation and release characteristics of BSA from the matrix gel beads made of calcium pectinate were studied. BSA release studies under conditions mimicking mouth to colon transit have shown that calcium pectinate protects the drug from being released completely in the physiological environment of the upper gastrointestinal tract, and is susceptible to the enzymatic action with consequent drug release. In addition, the release of BSA from CPG beads was strongly affected by calcium concentration and drying condition. However, the release was not particularly affected by the presence of hardening agent at the concentration of 1% or lower. Since the release of BSA as a model protein drug could be controlled by the regulation of the preparation conditions of CPG beads, the CPG beads may be used for a potential oral controlled release system for protein drugs.
Publisher: Oxford University Press (OUP)
Date: 2022
Abstract: New technologies developed to improve survival outcomes for glioblastoma (GBM) continue to have limited success. Recently, image-guided dose painting (DP) radiotherapy has emerged as a promising strategy to increase local control rates. In this study, we evaluate the practical application of a multiparametric MRI model of glioma infiltration for DP radiotherapy in GBM by measuring its conformity, feasibility, and expected clinical benefits against standard of care treatment. Maps of tumor probability were generated from perfusion/diffusion MRI data from 17 GBM patients via a previously developed model of GBM infiltration. Prescriptions for DP were linearly derived from tumor probability maps and used to develop dose optimized treatment plans. Conformity of DP plans to dose prescriptions was measured via a quality factor. Feasibility of DP plans was evaluated by dose metrics to target volumes and critical brain structures. Expected clinical benefit of DP plans was assessed by tumor control probability. The DP plans were compared to standard radiotherapy plans. The conformity of the DP plans was & %. Compared to the standard plans, DP (1) did not affect dose delivered to organs at risk (2) increased mean and maximum dose and improved minimum dose coverage for the target volumes (3) reduced minimum dose within the radiotherapy treatment margins (4) improved local tumor control probability within the target volumes for all patients. A multiparametric MRI model of GBM infiltration can enable conformal, feasible, and potentially beneficial dose painting radiotherapy plans.
Publisher: Elsevier BV
Date: 2008
Publisher: Springer Science and Business Media LLC
Date: 06-05-2008
Publisher: Elsevier BV
Date: 2008
Publisher: Trans Tech Publications, Ltd.
Date: 04-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.506.274
Abstract: Binding of bile salts by dietary fiber is believed to promote their excretion and hence to reduce the serum cholesterol level in man and experimental animals. In this study, the binding efficiency of soluble pectin from various sources, i.e., apple, citrus and pomelo, was examined. Sodium deoxycholate and sodium cholate hydrate were used as a model to represent bile salt in human body. The binding efficiency was assayed by acid reaction, thin layer chromatography (TLC) and enzyme cycling method. The results demonstrated that enzyme cycling method was the most suitable for assaying the in-vitro binding of bile salts while the TLC was not very sensitive, i.e., low amount of bile salts cannot be detected by TLC. Excess pectin from binding test could also interfere the acid reaction method even though the centrifugation was used to remove the excess pectin. When the concentration of pectin was increased, the binding efficiency with sodium deoxycholate increased. However, at 1% w/w of pectin, the binding efficiency decreased. The exception is for pomelo pectin in which the binding efficiency increased when the pectin concentration increased. With sodium cholate hydrate, only slight difference in binding efficiency was observed for all types and concentrations of pectin. The results indicate that the ability to bind bile salts of pectin might be responsible for its hypocholesterolemic action observed in experimental animals and humans.
Publisher: Elsevier BV
Date: 2010
Publisher: Trans Tech Publications, Ltd.
Date: 08-2011
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.317-319.185
Abstract: The aim of this study was to manufacture the ternary solid dispersions composed of nifedipine, Eudragit ® E and adsorbent. Dissolution enhancement of nifedipine was also investigated. The inert solid carriers were added in the mixtures of nifedipine and Eudragit ® E at varying ratios. The physicochemical properties of ternary systems, compared to physical mixtures, were analyzed using powder x-ray diffraction (PXRD) and differential scanning calorimetry (DSC). The dissolution of nifedipine from ternary systems was compared to the drug alone. The influence of drug:polymer: adsorbent ratio and type of adsorbent on the dissolution rate of the drug was also evaluated. The PXRD and DSC results of the systems with high amount of polymer showed that the drug was present in an amorphous form. On the other hand, the diffraction patterns and DSC thermograms of the physical mixtures revealed that to some extent the drug was present in a crystalline form. The results from this study demonstrated that an improvement in dissolution rate of nifedipine with Eudragit ® E and adsorbents was obtained.
Publisher: Trans Tech Publications, Ltd.
Date: 2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.93-94.362
Abstract: The aim of our study was to evaluate the applicability of yam (Dioscorea sp.) starch and arrowroot (Maranta arundinacea) starch as suspending agents in suspension. Paracetamol was used as a model drug because of its low solubility. It was found that the optimal concentration as suspending agent in paracetamol suspension was in the range of 7-8% for yam starch and 5-6% for arrowroot starch. All formulations were stable within the period of study with pH of 5.4-6.9. These results were comparable to those obtained from the sodium carboxymethyl cellulose (sodium CMC) which is a common suspending agent. It could be concluded that yam starch and arrowroot starch showed suspending activity in paracetamol suspension and could be applied as commercial suspending agent.
Publisher: Elsevier BV
Date: 09-2018
Publisher: Trans Tech Publications, Ltd.
Date: 04-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.506.319
Abstract: Biopolymeric particles can be formed by electrostatic complexes of globular proteins and anionic polysaccharides mixtures at pH values above pK a of anionic polysaccharide and under the isoelectric point of protein. The purpose of this study was to investigate the effect of protein (i.e., zein) concentration on the formation of complexes between zein and polysaccharide (i.e., amidated low methoxy pectin) in aqueous solution. The zeta potential, turbidity and morphology under different conditions were observed to provide insights into the physicochemical properties of zein-pectin complexes. The biopolymeric particles were obtained at pH 4 and concentration of zein and pectin of 0.001 and 1% w/w, respectively. As the zein concentration increased, the turbidity of zein-pectin solutions increased, resulting from the formation of zein-pectin complexes. The zeta potential of the systems became less negative when the zein concentration increased. The results suggested that concentration of zein primarily influenced the formation of zein-pectin complexes.
Publisher: Trans Tech Publications, Ltd.
Date: 08-2013
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.747.143
Abstract: The ability of self-emulsifying drug delivery system (SEDDS), which is a mixture of oils, surfactants and co-surfactants, to improve dissolution rate of a poorly water-soluble drug, manidipine hydrochloride (MDP), was evaluated in this study. Liquid form of SEDDS containing caprylic/capric glyceride, polyoxyl 35 castor oil, and diethylene glycol monoethyl ether at a weight ratio of 1:1:8 was converted to solid SEDDS by adsorption on to different solid carriers, i.e., Aerosil ® 200 and Sylysia ® 320. The results demonstrated that the solid carrier of at least 50% (w/w) was required to adsorb liquid SEDDS containing MDP. The results from powder X-ray diffraction, differential scanning colorimetry and scanning electron microscopy showed that MDP in solid SEDDS formulations was in amorphous form while a crystalline form was observed only in MDP raw material and its physical mixture. The in vitro dissolution of MDP from solid SEDDS using Sylysia ® 320 was higher than that using Aerosil ® 200 as a solid carrier. In summary, the solid SEDDS could be used as a carrier to improve the dissolution of MDP, a poorly water-soluble drug.
Publisher: Elsevier BV
Date: 2021
DOI: 10.1016/J.ARTMED.2021.102230
Abstract: Radiological images play a central role in radiotherapy, especially in target volume delineation. Radiomic feature extraction has demonstrated its potential for predicting patient outcome and cancer risk assessment prior to treatment. However, inherent methodological challenges such as severe class imbalance, small training s le size, multi-centre data and weak correlation of image representations to outcomes are yet to be addressed adequately. Current radiomic analysis relies on segmented images (e.g., of tumours) for feature extraction, leading to loss of important context information in surrounding tissue. In this work, we examine the correlation between radiomics and clinical outcomes by combining two data modalities: pre-treatment computerized tomography (CT) imaging data and contours of segmented gross tumour volumes (GTVs). We focus on a clinical head & neck cancer dataset and design an efficient convolutional neural network (CNN) architecture together with appropriate machine learning strategies to cope with the challenges. During the training process on two cohorts, our algorithm learns to produce clinical outcome predictions by automatically extracting radiomic features. Test results on two other cohorts show state-of-the-art performance in predicting different clinical endpoints (i.e., distant metastasis: AUC = 0.91 loco-regional failure: AUC = 0.78 overall survival: AUC = 0.70 on segmented CT data) compared to prior studies. Furthermore, we also conduct extensive experiments both on the whole CT dataset and a combination of CT and GTV contours to investigate different learning strategies for this task. For ex le, further experiments indicate that overall survival prediction significantly improves to 0.83 AUC by combining CT and GTV contours as inputs, and the combination provides more intuitive visual explanations for patient outcome predictions.
Publisher: Elsevier BV
Date: 04-2015
Publisher: IOP Publishing
Date: 10-03-2023
Abstract: Objective. To provide an open-source software for repeatable and efficient quantification of T 1 and T 2 relaxation times with the ISMRM/NIST system phantom. Quantitative magnetic resonance imaging (qMRI) biomarkers have the potential to improve disease detection, staging and monitoring of treatment response. Reference objects, such as the system phantom, play a major role in translating qMRI methods into the clinic. The currently available open-source software for ISMRM/NIST system phantom analysis, Phantom Viewer (PV), includes manual steps that are subject to variability. Approach. We developed the Magnetic Resonance BIomarker Assessment Software (MR-BIAS) to automatically extract system phantom relaxation times. The inter-observer variability (IOV) and time efficiency of MR-BIAS and PV was observed in six volunteers analysing three phantom datasets. The IOV was measured with the coefficient of variation (CV) of percent bias (%bias) in T 1 and T 2 with respect to NMR reference values. The accuracy of MR-BIAS was compared to a custom script from a published study of twelve phantom datasets. This included comparison of overall bias and %bias for variable inversion recovery ( T 1 VIR ), variable flip angle ( T 1 VFA ) and multiple spin-echo ( T 2 MSE ) relaxation models. Main results. MR-BIAS had a lower mean CV with T 1 VIR (0.03%) and T 2 MSE (0.05%) in comparison to PV with T 1 VIR (1.28%) and T 2 MSE (4.55%). The mean analysis duration was 9.7 times faster for MR-BIAS (0.8 min) than PV (7.6 min). There was no statistically significant difference in the overall bias, or the %bias for the majority of ROIs, as calculated by MR-BIAS or the custom script for all models. Significance. MR-BIAS has demonstrated repeatable and efficient analysis of the ISMRM/NIST system phantom, with comparable accuracy to previous studies. The software is freely available to the MRI community, providing a framework to automate required analysis tasks, with the flexibility to explore open questions and accelerate biomarker research.
Publisher: Elsevier BV
Date: 09-2018
Publisher: Elsevier BV
Date: 09-2010
Publisher: Elsevier BV
Date: 02-2011
DOI: 10.1016/J.EJPB.2010.11.019
Abstract: Magnetic resonance imaging (MRI) was used to assess in situ swelling behaviors of spray-dried chitosan acetate (CSA) in 0.1N HCl, pH 6.8 and pH 5.0 Tris-HCl buffers. The in vitro drug releases from CSA matrix tablets containing the model drugs, diclofenac sodium and theophylline were investigated in all media using USP-4 apparatus. The effect of chitosan molecular weight, especially in pH 6.8 Tris-HCl, was also studied. In 0.1N HCl, the drug release from the matrix tablets was the lowest in relation to the highest swelling of CSA. The swelling kinetics in Tris-HCl buffers are Fickian diffusion according to their best fit to Higuchi's model as well as the drug release kinetics in all the media. The high swelling rate (k(s)(')) was found to delay the drug release rate (k'). The linear relationship between the swelling and fractions of drug release in Tris-HCl buffers was observed, indicating an important role of the swelling on controlling the drug release mechanism. Additionally, CSA of 200 and 800 kDa chitosan did not swell in pH 6.8 Tris-HCl but disintegrated into fractions, and the drug release from the matrix tablets was the highest.
Publisher: Elsevier BV
Date: 02-2008
DOI: 10.1016/J.EJPB.2007.05.017
Abstract: A colonic drug delivery with a new concept based on a combination of time-, pH-, and enzyme-controlled system was developed. Spray-dried chitosan acetate (CSA) prepared from low molecular weight chitosan was characterized. A combination of CSA and hydroxypropyl methylcellulose (HPMC) was used as new compression-coats for 5-aminosalicylic acid (5-ASA) tablets. Factors affecting in-vitro drug release, i.e. % weight ratio of coating polymers, enzyme activity, pH of media, and excipients in core tablets, were evaluated. The tablets compression-coated with HPMC:CSA at 60:40 and 50:50% weight ratio providing lag times about 5-6h were able to pass through the stomach (stage I, 0.1N HCl) and small intestine (stage II, pH 6.8, Tris-HCl). The delayed release was time- and pH-controlled owing to the swelling with gradual dissolving of CSA and HPMC in 0.1N HCl and the less solubility of CSA at higher pH. After reaching the colon (stage III, pH 5.0, acetate buffer), the dissolution of CSA at low pH triggered the drug release over 90% within 14h. Furthermore, the degradation of CSA by beta-glucosidase in the colonic fluid enhanced the drug release while adding the disintegrant or the osmotic agent in the core tablets would affect the drug release.
Publisher: Springer Science and Business Media LLC
Date: 2007
DOI: 10.1208/PT0803079
Abstract: The aim of this study was to examine the effect of pellet size, pectin type, pectin concentration, and dissolution medium on the swelling and drug release behavior of spherical pellets containing theophylline and coated with 2 different calcium pectinates, using a multi-level factorial design approach. The spherical pellets were prepared by an extrusion-spheronization method and then coated with calcium pectinate using the diffusion-controlled interfacial complexation technique, which provides a defect-free and uniform coating on solid cores. Theophylline release from the pellets was slowed by the application of the coatings. The time to release 50% of the payload (ie, T50) in an acidic medium was approximately 7 minutes from uncoated small pellets and was 55 minutes after an amidated calcium pectinate coat was applied a comparable coat on large pellets showed a T50 of 93 minutes. Drug release profiles of dry coated pellets showed a lag time (all less than 20 minutes) when the gel coat hydrated and swelled, followed by a zero-order release. It was found that the release rate was controlled by the pellet size, pectin type, pectin concentration, and dissolution medium.
Publisher: Elsevier BV
Date: 08-2007
DOI: 10.1016/J.EJPB.2006.11.007
Abstract: The aim of this study was to investigate the possibility of producing alginate-based pellets by extrusion/spheronization and also to improve the formation of spherical alginate-based pellets by investigating the effect of additive in granulating liquid on characteristics and drug release from resulting pellets. Two types of sodium alginate (30%) were evaluated in combination with theophylline (20%), microcrystalline cellulose (50%) and different granulation liquids. The pellets were then prepared in a basket extruder, then spheronized and dried. The final products were characterized by morphological examination and drug release study. Different additives in the granulating liquid influenced the ability of the extruded mass to form pellets (the processability) with this technique. However, different sodium alginate types responded to shape modifications to a different extent. Long, dumbbell-shaped pellets were obtained with viscous granulating liquids. However, short, nearly spherical pellets were obtained with watery granulation liquid with calcium chloride that reduced the swelling ability of sodium alginate. Improvements in the pellet characteristics were also dependent on the sodium alginate type employed. Most of pellet formulations released about 75-85% drug within 60min and showed a good fit into both Higuchi and Korsmeyer-Peppas equations. Higher amount of 3% calcium chloride, as a granulating liquid, in the formulation showed higher mean dissolution time resulting from the cross-linking properties of calcium ions to the negative charges of alginate molecules.
Publisher: Trans Tech Publications, Ltd.
Date: 2010
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.93-94.358
Abstract: As a new processing method for the production of modified starch, microwave heating was applied to native arrowroot starch. The effect of processing parameter on the sustained release properties of the obtained modified starches was investigated. The modified starch was blended with a model drug, theophylline, and then compressed into tablet using hydraulic press at a pressure of 19.6 kN for 30 s. The physical properties as well as drug release behavior of the compressed tablets were investigated. The results showed that the physical properties of different modified starches were about the same. The modified arrowroot starch displayed better sustained release properties than native starch. The modified arrowroot starch, which subjected to microwave heating using high level of water content, long heating time and high microwave power, demonstrated promising properties as hydrophilic matrix excipients for sustained release tablets.
Publisher: Trans Tech Publications, Ltd.
Date: 08-2013
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.747.139
Abstract: Lipid-based formulations (LBF) including self-emulsifying drug delivery system have been used to improve drug dissolution and bioavailability by avoiding rate-limiting step during dissolution of poorly water-soluble drugs. This study was aimed to investigate the behavior of lipid-based formulations upon dilution in aqueous media by using small angle X-ray scattering (SAXS). LBF is composed of oil (caprylic/capric glyceride), surfactants (polyoxyl 35 castor oil or polyoxyl 40 hydrogenated castor oil), and co-solvent (diethylene glycol monoethyl ether) at a weight ratio of 1:1:8. Nifedipine, a poorly water-soluble drug, was used as a model drug. A 100-fold dilution of the LBF in aqueous media (i.e., simulated gastric fluid USP without pepsin (SGF) and distilled water) resulted in nanosized emulsion (less than 200 nm). The selected formulations were diluted in aqueous media at various ratios (e.g., 0.01, 0.02, 0.04, 0.06, 0.09, 0.11, 0.18, 0.25, 0.67, 1.5, 4, 99, 199 and 300 folds) and then, after equilibrium, monitored by SAXS in order to observe the surfactant rearrangement. The results from SAXS scattering curves ( q of 0.027-0.980 Å -1 ) demonstrated that a lamellar phase or liquid crystalline was not formed upon dilution. The emulsions were formed without the ordered structure.
Publisher: Elsevier BV
Date: 06-2015
Publisher: Elsevier BV
Date: 03-2011
Publisher: Springer Science and Business Media LLC
Date: 09-2004
DOI: 10.1208/AAPSJ060324
Publisher: Trans Tech Publications, Ltd.
Date: 12-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.1060.227
Abstract: To overcome major side-effects, that is, cardiotoxicity of doxorubicin (DOX), pH-responsive dextrin nanogels (DNGs) were developed for using as a smart drug carrier. DOX-loaded DNGs were fabricated by emulsion cross-linking technique using glyoxal as a cross-linking agent to form acid-sensitive, acetal bonds. The objective of this study was to investigate the cytotoxicity of DOX-loaded DNGs on the human osteosarcoma 143B cell line. The cytotoxicity assay results showed that DOX-loaded DNGs retained high cell inhibition efficiency in 143B cells in a concentration- and treatment time-dependent manner. The cytotoxicity decreased with increasing ratio of glyoxal to dextrin. Observation of 143B cells by light microscopy showed the morphological changes after treatment with DOX-loaded DNGs. These results suggested that DOX-loaded DNGs with pH-sensitive properties is promising for use as a drug delivery system for cancer therapy.
Publisher: Trans Tech Publications, Ltd.
Date: 08-2013
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.747.131
Abstract: Modified starches have been widely used as an excipient in matrix tablets to control drug release. A new processing method for the production of modified starch, high power ultrasonic treatment (400 W), was applied to native tapioca starch. The spray drying technique was used after modification (i.e., by ultrasonic or heat treatment). Matrix tablets were then prepared by direct compression using theophylline as a model drug. The effect of starch modification on swelling, erosion and in vitro drug release behaviors of compressed matrices was investigated in 0.1 N HCl or phosphate buffer (pH 6.8). The matrix tablets of modified tapioca starch formed a continuous gel layer while in contact with the aqueous medium undergoing a combination of swelling and erosion. The ultrasound-treated starch swelled and eroded less than the native starch and heat-treated starch, thus the drug release from matrix tablets using ultrasound-treated starch was slower. For these results, it can be concluded that the ultrasound-treated starch was a promising excipient for controlled drug release.
Publisher: Trans Tech Publications, Ltd.
Date: 12-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.1060.103
Abstract: Recently, nanoparticulate system has been applied to deliver drug to colon because this system can increase drug absorption, prolong drug staying in gastrointestinal tract and also minimize chance of dose dumping effect. In this study, nanoparticles (NPs) developed for colonic drug delivery were fabricated via electrohydrodynamic atomization (EHDA) to find suitable formulation and preparation conditions. The NPs were prepared by dissolving prednisolone (model drug) and Eudragit ® S100 (EDS100) in methanol, ethanol, isopropanol, butanol and mixtures of ethanol with purified water in various drug olymer weight ratio and polymer concentrations. After that, the prepared solution was injected using the EHDA machine. The preparation condition and the instrument parameters such as applied voltage, injected distance, feed rate, and drum collector rolling rate were delicately adjusted again to obtain blank and drug loaded NPs. The NPs papered from methanol offered spherical particles with diameter size of 422 nm. The products of isopropanol and butanol were shrinkage particles. The sprayed products were changed from particle to fiber when using the spraying solution prepared from high concentration of EDS100. More fiber product was obtained when high applied voltage (20kV) was utilized. Prednisolone loaded NPs were also fabricated by EHDA. SEM and zeta-potential results reveal that prednisolone was entrapped in the NPs. All the drug loaded NPs products were in spherical shape with average diameter size of 448.60-660.98 nm and the maximum drug encapsulation was 92.65%. From the preliminary result, this nanoparticulate system expresses possibility to fabricate specific colonic drug delivery.
Publisher: Elsevier BV
Date: 2017
Publisher: Elsevier BV
Date: 03-2017
Publisher: Informa UK Limited
Date: 1999
Abstract: Polymeric hydrogels are widely used as controlled-release matrix tablets. In the present study, we investigated high-methoxy pectins for their potential value in controlled-release matrix formulations. The effects of compression force, ratio of drug to pectin, and type of pectin on drug release from matrix tablets were also investigated. The results of the in vitro release studies show that the drug release from compressed matrix tablets prepared from pectin can be modified by changing the amount and the type of pectin in the matrix tablets. However, compression force did not significantly affect the drug release. The mechanisms controlling release rate were discussed with respect to drug diffusion through the polymer matrices, but may be more complex.
Publisher: Elsevier BV
Date: 11-2003
DOI: 10.1016/J.IJPHARM.2003.08.005
Abstract: The internal structure of pharmaceutical solid dosage forms is commonly revealed by secondary electron imaging using standard scanning electron microscopy (SEM) technique. In this work we propose a back-scattered electron imaging (BEI) as a new tool for examining the matrix structure of calcium pectinate beads. Imaging s les with back-scattered electrons in the SEM is based on material or atomic number contrast. High atomic number elements, such as calcium, reflect more electrons and appear bright on electron micrographs. The BEI-SEM images of calcium pectinate matrix beads clearly showed net-like structure of calcium pectinate and uniform distribution of drug particles. The matrix compositions were confirmed by energy dispersive analyzer. The result demonstrates the advantageous of BEI for examining the matrix structure of calcium pectinate.
Publisher: MDPI AG
Date: 25-04-2022
DOI: 10.3390/PHARMACEUTICS14050935
Abstract: Chitosan is a natural biopolymer that is present in an abundant supply in sources such as crustacean shells, mushrooms, and insect exoskeletons. It can be used to make a variety of types of drug formulations and is generally safe to use in vivo plus, it has inherent cholesterol-reducing properties. While an abundance of papers has tested this biopolymer in nanoparticles in cancer and diabetes research, there is a lag of usage, and hence the paucity of information, in the area of cardiovascular research, specifically in atherosclerosis, the topic of this review. This review highlights some of the deficiencies in this niche area of research, examines the range of chitosan nanoparticles that have been researched to date, and proposes several ways forward to advance this field. Nanoparticles used for both diagnostic and therapeutic purposes are reviewed, with a discussion on how these nanoparticles could be better researched in future and what lays ahead as the field potentially moves towards clinical trials in future.
Publisher: Wiley
Date: 11-03-2023
DOI: 10.1002/APP.53835
Abstract: The lack of biopolymer filament has been recognized as a significant challenge to fused filament fabrication (FFF) or fused deposition modeling (FDM) 3D printing. According to the restricted choice, shellac is a natural polymer of interest due to its thermoplastic property at a low temperature. The purpose of this study was to evaluate the feasibility of applying shellac as a candidate biopolymer for FFF 3D printing filaments. Shellac matrices and plasticized shellac matrices of varying grades of polyethylene glycol (PEG) were prepared using hot melt processes, and their physicochemical properties and filament properties were investigated. The results showed that a shellac matrix could be easily prepared at 80°C and stayed stable for up to 12 h. The addition of PEG could improve the stability of the shellac matrix as demonstrated by a slight deviation in acid value, percent insoluble solid, and FTIR spectra after annealing for 24 h. The shellac filaments with acceptable appearance and mechanical properties were also produced at 80 ± 5°C by the incorporation of 10–20% w/w of PEG 4000 or PEG 10000. Therefore, SHL‐PEG might be a good candidate material for the fabrication of 3D printing filament, especially at low extrusion temperature.
Publisher: Springer Science and Business Media LLC
Date: 21-08-2010
Publisher: Trans Tech Publications, Ltd.
Date: 12-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.1060.45
Abstract: The main objective of this study was to fabricate biopolymer-based microbeads, providing enteric properties and controlled release of diclofenac sodium, using layer-by-layer technique. The calcium pectinate microbeads have been designed and coated with chitosan and pectin multilayers. Drug release was performed in simulate gastric fluid (pH 1.2) for 2 hours, followed by pH 6.8 buffer for 8 hours. The effects of chitosan concentration, number of layer and drying technique on drug release were investigated. The results showed that the calcium pectinate microbeads could be simply prepared by ionotropic gelation and then coated with chitosan and pectin solutions using layer-by-layer procedure. The diameter of the microbeads ranged from 800 to 1000 μm for air-dried s les and from 1 to 2 mm for freeze-dried s les. The freeze-dried microbeads had a rough surface and many pores inside, as observed by SEM. The microbeads coated with 4% chitosan/4% pectin revealed a slower drug release than those coated with 1% chitosan/4% pectin and demonstrated a controlled release pattern. Moreover, different drying techniques and numbers of layer also influenced drug release behavior of the prepared microbeads.
Publisher: Elsevier BV
Date: 2013
Publisher: Trans Tech Publications, Ltd.
Date: 04-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.506.497
Abstract: In development of effervescent-based floating tablets, acrylic polymer is used to prepare a gas-entrapped membrane of the system. The tackiness of this acrylic polymer film causes tablet agglomeration, leading to failure in floatation. Thus, the aim of this study was to investigate the effect of magnesium stearate (MS) used as anti-tacking agent on mechanical and wetting properties of the acrylic polymer (Eudragit ® RL 30D) films. Incorporating MS resulted in the films with a slightly lowered puncture strength, a highly lowered elongation and an increased contact angle. These results indicated that flexibility and wettability of these films were reduced by addition of MS. Furthermore, the film tackiness measurement by peel test showed that 5% (w/w) of MS could significantly decrease the tackiness of the films. It was demonstrated that MS was a promising candidate to be used as an anti-tacking agent for effervescent-based floating tablets.
Publisher: Trans Tech Publications, Ltd.
Date: 08-2013
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.747.127
Abstract: The purpose of this study was to investigate the influence of pH on properties and stability of oil-in-water emulsions using pectin as an emulsifier and zein as an auxillary emulsifier. Primary emulsions were prepared by mixing rice bran oil with anionic polysaccharide, pectin, at pH 4 or 7. Zein solution was then added in order to prepare secondary emulsions. Final concentration of secondary emulsions was 20% (w/w) rice bran oil, 2% (w/w) pectin and 0.5% (w/w) zein. The results demonstrated that emulsions prepared at pH 4 were smaller in size, higher viscosity, and more stable after stability test than those prepared at pH 7. Light microscopic images showed that, at pH 7, emulsion droplets were aggregated. At pH 7, both pectin and zein represented as negative charge and no complex was formed, leading to the less stable emulsions. Below the isoelectric point (pH 5.5) of zein, i.e. at pH 4, zein molecules represented as positive charge and pectin represented as negative charge, resulting in a light cross-linking polymer network. It is possible that a low concentration of zein helps to stabilize the emulsions by improving the rigidity of coated layer on oil droplets, thus reducing the depletion flocculation to occur. The stabilizing effect in presence of zein, at pH 4, is attributed to a pectinzein complex formation at the interface.
Publisher: MDPI AG
Date: 03-10-2021
DOI: 10.3390/PHARMACEUTICS13101607
Abstract: The purpose of this study was to investigate the impact of the drug loading method on drug release from 3D-printed tablets. Filaments comprising a poorly water-soluble model drug, indomethacin (IND), and a polymer, polyvinyl alcohol (PVA), were prepared by hot-melt extrusion (HME) and compared with IND-loaded filaments prepared with an impregnation (IMP) process. The 3D-printed tablets were fabricated using a fused deposition modeling 3D printer. The filaments and 3D printed tablets were evaluated for their physicochemical properties, swelling and matrix erosion behaviors, drug content, and drug release. Physicochemical investigations revealed no drug–excipient interaction or degradation. IND-loaded PVA filaments produced by IMP had a low drug content and a rapid drug release. Filaments produced by HME with a lower drug content released the drug faster than those with a higher drug content. The drug content and drug release of 3D-printed tablets containing IND were similar to those of the filament results. Particularly, drug release was faster in 3D-printed tablets produced with filaments with lower drug content (both by IMP and HME). The drug release of 3D-printed tablets produced from HME filaments with higher drug content was extended to 24 h due to a swelling-erosion process. This study confirmed that the drug loading method has a substantial influence on drug content, which in turn has a significant effect on drug release. The results suggest that increasing the drug content in filaments might delay drug release from 3D-printed tablets, which may be used for developing dosage forms suited for personalized medicine.
Publisher: Informa Healthcare
Date: 13-05-2011
DOI: 10.1517/17425247.2011.584867
Abstract: Biopolymers have been used extensively in the pharmaceutical field. Pectin, a biopolymer, has several unique properties that enable it to be used as an excipient or carrier for oral drug delivery systems. Accordingly, several investigators have identified the benefits of pectin-based delivery systems for oral drug administration. This review first describes the chemical structure, source and production, degree of esterification and gel formation properties of pectin. The application of pectin in various oral drug delivery platforms is also discussed, that is, controlled release systems, gastro-retentive systems, colon-specific delivery systems and mucoadhesive delivery systems. Pectin from different sources provides different gelling abilities, due to variations in molecular size and chemical composition. Like other natural polymers, a major problem with pectin is inconsistency in reproducibility between s les, which may result in poor reproducibility in delivery characteristics. Scintigraphic studies and in vivo studies, in both animals and human volunteers, demonstrate the successful development of a pectin-based colon-specific drug delivery system. Pectin-based controlled release systems, gastro-retentive systems and mucoadhesive systems present promising approaches for increasing the bioavailability of drugs, but are in their infancy. A lack of direct correlation between in vitro release and in vivo absorption studies is a major concern with these systems.
Publisher: Oxford University Press (OUP)
Date: 02-08-2012
DOI: 10.1111/J.2042-7158.2012.01567.X
Abstract: The frontline drug doxorubicin has been used for treating cancer for over 30 years. While providing a cure in select cases, doxorubicin causes toxicity to most major organs, especially life-threatening cardiotoxicity, which forces the treatment to become dose-limiting. Doxorubicin is known to bind to DNA-associated enzymes, intercalate with DNA base pairs, and target multiple molecular targets to produce a range of cytotoxic effects. For instance, it causes the activation of various molecular signals from AMPK (AMP-activated protein kinase inducing apoptosis) to influence the Bcl-2/Bax apoptosis pathway. By altering the Bcl-2/Bax ratio, downstream activation of different caspases can occur resulting in apoptosis. Doxorubicin also induces apoptosis and necrosis in healthy tissue causing toxicity in the brain, liver, kidney and heart. Over the years, many studies have been conducted to devise a drug delivery system that would eliminate these adverse affects including liposomes, hydrogel and nanoparticulate systems, and we highlight the pros and cons of these drug delivery systems. Overall the future for the continued use of doxorubicin clinically against cancer looks set to be prolonged, provided certain enhancements as listed above are made to its chemistry, delivery and toxicity. Increased efficacy depends on these three aims being met satisfactorily as discussed in turn in this review.
Publisher: Wiley
Date: 19-06-2021
Abstract: Research in artificial intelligence for radiology and radiotherapy has recently become increasingly reliant on the use of deep learning‐based algorithms. While the performance of the models which these algorithms produce can significantly outperform more traditional machine learning methods, they do rely on larger datasets being available for training. To address this issue, data augmentation has become a popular method for increasing the size of a training dataset, particularly in fields where large datasets aren’t typically available, which is often the case when working with medical images. Data augmentation aims to generate additional data which is used to train the model and has been shown to improve performance when validated on a separate unseen dataset. This approach has become commonplace so to help understand the types of data augmentation techniques used in state‐of‐the‐art deep learning models, we conducted a systematic review of the literature where data augmentation was utilised on medical images (limited to CT and MRI) to train a deep learning model. Articles were categorised into basic, deformable, deep learning or other data augmentation techniques. As artificial intelligence models trained using augmented data make their way into the clinic, this review aims to give an insight to these techniques and confidence in the validity of the models produced.
Publisher: Elsevier BV
Date: 06-2008
DOI: 10.1016/J.IJPHARM.2008.03.009
Abstract: The aim of this paper was to study the swelling and diffusion behaviors of calcium polysaccharide gel (CaPG) films prepared by an interfacial complexation technique, a new gel formation method that allowed calcium ions to diffuse from a source to form gel films with polysaccharide (i.e., alginate or pectin). The dynamic swelling behavior of CaPG films showed that swelling was a function of time. Most CaPG films showed a maximum amount of water absorption during the first few hours. The films swelled less in water and acidic media but extensively swelled in 0.1M NaCl. The rehydration of the dry films in the acidic media or the 0.1M NaCl solution also lead to the extraction of most of the calcium ions from the CaPG within 4h or less. Partitioning and diffusion of a model drug, theophylline (TPL), were measured through CaPG films equilibrated in different media. The partition and diffusion coefficients of TPL through CaPG films were found to vary, depending upon polysaccharide type, concentration and equilibration medium. The results suggest that both partition and pore mechanisms operated concurrently in the transport of TPL through CaPG films equilibrated in different media.
Publisher: Elsevier BV
Date: 02-2009
DOI: 10.1016/J.EJPB.2008.08.002
Abstract: Spray-dried chitosan acetate (CSA) and ethylcellulose (EC) were used as new compression coats for 5-aminosalicylic acid tablets. Constrained axial or radial swelling of pure CSA and EC/CSA tablets in 0.1 N HCl (stage I), Tris-HCl, pH 6.8 (stage II), and acetate buffer, pH 5.0 (stage III), was investigated. Factors affecting in vitro drug release, i.e., % weight ratios of coating polymers, dip speeds of dissolution apparatus or pH of medium or colonic enzyme (beta-glucosidase) in stage III, and use of a super disintegrant in core tablets, were evaluated. Swollen CSA gel dissolved at lower pH and became less soluble at higher pH. The mechanism of swelling was Fickian diffusion fitting well into both Higuchi's and Korsmeyer-Peppas models. EC:CSA, at 87.5:12.5% weight ratio, provided lag time rendering the tablets to reach stage III (simulated colonic fluid of patients), and the drug was released over 90% within 12 h. The system was a dual time- and pH-control due to the insolubility of EC suppressing water diffusion and the swelling of CSA in the stages I and II. The erosion of CSA gel in the stage III induced the disintegration of the coat resulting in rapid drug release. The lower dip speed and higher pH medium delayed the drug release, while a super disintegrant in the cores enhanced the drug release and no enzyme effect was observed.
Publisher: Elsevier BV
Date: 06-2011
DOI: 10.1016/J.IJPHARM.2011.03.019
Abstract: The aim of this study was to investigate the effect of source variation of hydroxypropyl methylcellulose (HPMC) raw material on prediction of drug release from HPMC matrix tablets. To achieve this objective, the flow ability (i.e., angle of repose and Carr's compressibility index) and apparent viscosity of HPMC from 3 sources was investigated to differentiate HPMC source variation. The physicochemical properties of drug and manufacturing process were also incorporated to develop the linear regression model for prediction of drug release. Specifically, the in vitro release of 18 formulations was determined according to a 2 × 3 × 3 full factorial design. Further regression analysis provided a quantitative relationship between the response and the studied independent variables. It was found that either apparent viscosity or Carr's compressibility index of HPMC powders combining with solubility and molecular weight of drug had significant impact on the release behavior of drug. The increased drug release was observed when a greater in drug solubility and a decrease in the molecular weight of drug were applied. Most importantly, this study has shown that the HPMC having low viscosity or high compressibility index resulted in an increase of drug release, especially in the case of poorly soluble drugs.
Publisher: Elsevier BV
Date: 10-2006
DOI: 10.1016/J.EJPS.2006.06.007
Abstract: Calcium alginate gel-coated pellets were developed by forming an insoluble gel coat on extruded-spheronized pellets by interfacial complexation. Experiments were designed to investigate the effect of pellet size, alginate type, alginate concentration, and dissolution medium on swelling and drug release behavior. Low swelling in acidic media was related to proton-calcium ion exchange forming insoluble acid gels. In contrast, partial formation of soluble sodium alginate in 0.1M NaCl induced water uptake, resulting in greater swelling. Drug release from coated pellets showed a lag time when the gel coat hydrated and swelled, followed by a zero-order release. Significantly slower release was observed when either the pellet size or the alginate concentration was increased. Alginate with high guluronic acid content gave the slowest release. Different types of alginate with high mannuronic acid content showed different release behaviors that are probably due to the different monomer sequences and botanical sources. The faster drug release in acidic media and 0.1M NaCl compared to water is probably due to reduced calcium cross-linking in the gel. These results suggest that the pellet size, alginate type and concentration and dissolution medium influenced the swelling and drug release behavior of calcium alginate gel-coated pellets.
Publisher: Informa UK Limited
Date: 06-2009
Publisher: Trans Tech Publications, Ltd.
Date: 12-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.1060.79
Abstract: The aim of this study was to prepare matrix beads made of enteric polymer, Eudragit ® L, metronidazole and various amounts of cetyl alcohol (0, 0.1 and 1%). Eudragit ® L, metronidazole and cetyl alcohol were dissolved in acetone and then extruded into dichloromethane. The influence of amount of cetyl alcohol on floating and drug release behavior of matrix beads of Eudragit ® L was investigated. The results showed that, after extruding, cetyl alcohol dissolved out from the beads already formed, resulting in a porous structure. Thus, the beads can float in simulated gastric fluid for more than 8 hours. Different amounts of cetyl alcohol had a slight effect on the drug release. However, the increased amount of cetyl alcohol in the formulations significantly sustained the drug release while the beads remained floating. The results suggest that Eudragit ® L beads could be used as a carrier for intragastric floating drug delivery.
Publisher: Elsevier BV
Date: 07-0008
DOI: 10.1016/J.EJPB.2007.01.010
Abstract: Mucoadhesive performance of various pectins with different degrees of esterification and molecular weights was examined with porcine gastrointestinal (GI) mucosa, i.e. buccal, stomach, small intestine and large intestine, using a texture analyzer equipped with mucoadhesive platform. The instrumental parameters and test conditions such as pre-hydration time of pectin disc, contact time, contact force, test speed of probe withdrawal, GI tissue and test medium were also studied. Two parameters derived from texture analysis, namely maximum detachment force (F(max)) and work of adhesion (W(ad)), were used as parameters for comparison of mucoadhesive performance. The results indicated that degree of hydration of pectin disc affected the mucoadhesive properties. The mucoadhesion of pectin increased with the increased contact time and contact force, but not by the increased probe withdrawal speed. Tissue from different parts of GI tract and test medium also influenced the mucoadhesion. Pectins showed a stronger mucoadhesion on large intestinal mucosa than on small intestinal mucosa. The mucoadhesive properties of pectins on gastric mucosa depended on pH of the medium a higher F(max) and W(ad) in a pH 4.8 medium than a pH 1.2 medium was revealed. Additionally, pectin showed a significantly higher mucoadhesion than carbomer934P in most of the GI mucosa tested. The results also demonstrated that the mucoadhesive performance of pectins largely depended on their characteristics, i.e. higher degree of esterification and molecular weight gave a stronger mucoadhesion. These findings suggest that pectin can be used as a mucoadhesive carrier for GI-mucoadhesive drug delivery systems.
Publisher: Elsevier BV
Date: 06-2016
Publisher: Elsevier BV
Date: 06-2019
Publisher: Trans Tech Publications, Ltd.
Date: 10-2011
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.152-153.1232
Abstract: The aim of this study was to investigate the effect of electrospinning process on the physical properties of fibers made from shellac. Electrospun shellac fiber was prepared by dissolving shellac in ethanol and then transferred to the electrospinning system. The influences of process parameters including electric field voltage, tip to collector gap, feeding rate and concentration of shellac solutions on the spinnability and properties of obtained shellac fibers were elucidated. The result demonstrated that micro-nano fibers of shellac were easily formed after spinning. The concentration of shellac solution was a crucial parameter that determined the spinnability. The electro-sprayed particles of shellac were achieved at the concentration of 35% w/w and lower while the electrospun fibers was formed in the concentration range of 40-45 % w/w. SEM pictures demonstrated that the beaded fiber structure obtained at 40-43% w/w was changed to the continuous fiber structure at 45% w/w. The diameter of fiber showed a tendency to increase while the size distribution of diameter was narrower as increasing voltage. The other optimized electrospinning parameters including feeding rate, tip to collector gap were 0.5-2 ml/h and 15-20 cm, respectively. In conclusion, the study demonstrated the critical parameters that determined the properties of required fibers. The knowledge gained should support the development of the drug incorporated electrospun shellac fiber in near future.
Publisher: Elsevier BV
Date: 09-1998
DOI: 10.1016/S0939-6411(98)00021-6
Abstract: Entrapment of cells within spheres of polysaccharide gel has become the most widely used technique for immobilizing living cells. Polysaccharide pectin, formed gel with calcium ions, was investigated as a precursor of spherical calcium polysaccharide gel beads. The type of pectin s le was found to be important in the formation of the beads. Partially deesterified pectin with a lower degree of esterification provided spherical beads and was chosen for immobilization of the yeast cells, Sacchararomyces cerevisiae, and compared to those with alginate. The effect of storage condition of the beads on the viability of the entrapped cells was also studied. After storage at 4 degreesC or -40 degreesC for 1 month, even lyophilization before storage, the beads with entrapped cells were sufficiently stable when compared to suspension of non-entrapped yeast cells.
Publisher: MDPI AG
Date: 09-12-2022
DOI: 10.3390/PHARMACEUTICS14122765
Abstract: Skin fungal infection is still a serious public health problem due to the high number of cases. Even though medicines are available for this disease, drug resistance among patients has increased. Moreover, access to medicine is restricted in some areas. One of the therapeutic options is herbal medicine. This study aims to develop an ethosome formulation loaded with Zingiber zerumbet (L.) Smith. rhizome extract for enhanced antifungal activity in deep layer skin, which is difficult to cure. Ethosomes were successfully prepared by the cold method, and the optimized formulation was composed of 1% (w/v) phosphatidylcholine and 40% (v/v) ethanol. Transmission electron microscope (TEM) images revealed that the ethosomes had a vesicle shape with a diameter of 205.6–368.5 nm. The entrapment of ethosomes was 31.58% and could inhibit the growth of Candida albicans at a concentration of 312.5 μg/mL. Finally, the ethosome system significantly enhanced the skin penetration and retention of the active compound (zerumbone) compared with the liquid extract. This study showed that Z. zerumbet (L.) rhizome extract could be loaded into ethosomes. The findings could be carried over to the next step for clinical application by conducting further in vivo penetration and permeation tests.
Publisher: Elsevier BV
Date: 02-2022
Publisher: American Scientific Publishers
Date: 07-2012
Publisher: Trans Tech Publications, Ltd.
Date: 08-2013
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.747.115
Abstract: traconazole (ITZ) polyethylene glycol 4000 (PEG) solid dispersions (SDs) containing hydroxypropyl methylcellulose (HPMC) and/or low methoxy pectin (LMP) were prepared by melting method at a ratio of drug to carrier of 1:9. ITZPEG formulations showed the highest drug release (83.51%) when compared to the formulations containing HPMC and/or pectin (i.e., 43.02%, 40.64% and 59.94% for those containing HPMC, LMP and HPMC+LMP, respectively). Powder X-ray diffractograms of all formulations revealed that the drug was present in an amorphous form while a crystalline form was observed only in ITZ or its physical mixture. After storage at accelerated condition (40°C, 75%RH) for 2 and 12 months, the crystalline of ITZ was clearly not observed in all SDs. All formulations showed an increase in mean dissolution time (MDT) but the formulations containing biopolymer showed the lower MDT than that containing no biopolymer. The results suggested that either HPMC or LMP in SDs can help to inhibit the recrystallization of amorphous ITZ in SD, probably by a polymer anti-plasticizing effect.
Publisher: MDPI AG
Date: 24-01-2022
DOI: 10.3390/GELS8020072
Abstract: Liquid plaster (LP) is a recently developed wound dressing product that can be used to cover wounds in various parts of the body, especially small injuries or wounds in body parts involved in movement. Given the benefits and applications of LP, this study aimed to develop and evaluate Chromolaena odorata extract-loaded LP with antimicrobial and hemostasis effects. The study was first conducted through the extraction of Choromolaena odorata leaf by using an ethanol maceration technique and identification of the compounds with high-performance liquid chromatography. The LP loaded with Chromolaena odorata extract demonstrates an ability to inhibit S. aureus and S. epidermidis at a MIC of 0.25 mg/mL and MBC of 0.5 mg/mL. The antioxidant activity test was performed by ABTS and DPPH methods demonstrating the free-radical scavenging activity of the extract. The blood clotting activity was established by varying the concentration of Choromolaena odorata leaf extract from 0.0625 mg/mL to 1 mg/mL. The formulation of the film-forming system was developed by varying the solvent, polymer, and plasticizer proportions. The optimum formulation displayed fast film-forming with high elasticity of the film. Moreover, the 20 mg/mL herbal extract-loaded LP provided an antibacterial effect with admissible water vapor transmission and low skin irritation. As a result, the study demonstrates the possibility of introducing the Chromolaena odorata extract-loaded LP to increase the effectiveness of wound healing and the antibacterial effect on the skin.
Publisher: MDPI AG
Date: 12-09-2022
DOI: 10.3390/PHARMACEUTICS14091922
Abstract: The goal of this study was to develop an add-on device for dry powder inhalers (Accuhaler) via 3D printing to improve drug administration efficiency in patients with limited inspiratory capacity, including young children, the elderly, and those with chronic obstructive pulmonary disease. With salmeterol xinafoate and fluticasone propionate as model active pharmaceutical ingredients (API), the emitted API doses were used to assess the effectiveness of the add-on device. The APIs were quantified by an HPLC assay validated for specificity, range, linearity, accuracy, and precision. The motor power of the add-on device could be regulated to moderate fan speed and the air flow in the assembled device. When 50–100% of the fan motor power of the add-on device was used, the emitted dose from the attached dry powder inhaler (DPI) was increased. A computational fluid dynamics application was used to simulate the air and particle flow in the DPI with the add-on device in order to elucidate the operating mechanism. The use of the add-on device combined with a sufficient inhalation flow rate resulted in a larger pressure drop and airflow velocity at the blister pocket. As these characteristics are associated with powder fluidization, entrainment, and particle re-suspension, this innovative add-on device might be utilized to enhance the DPI emitted drug dose for patients with low inspiratory rates and to facilitate the provision of adequate drug doses to achieve the treatment outcomes.
Publisher: Elsevier BV
Date: 11-2007
DOI: 10.1016/J.EJPS.2007.08.001
Abstract: The aim of this study was to investigate the effect of drug solubility on the release behavior from calcium polysaccharide gel (CaPG)-coated pellets. Three different drugs with similar chemical structure, but different water solubility, namely caffeine (CAF), theophylline (TPL) and theobromine (TBR), were used. Drug-loaded spherical pellets were manufactured by an extrusion-spheronization method. The CaPG was applied on the pellets loaded with different drugs by interfacial complexation coating. The encapsulation efficiency of coated pellets was found to vary from 57.6 to 84.3%, depending on the solubility of the active drug and polysaccharide type. Drug release from different uncoated pellets was relatively unaffected by pH and release media but depended mainly on drug solubility. Release behavior was significantly modified in the pellets coated with CaPG, for all of the drugs tested. Drug release from coated pellets of the different drugs showed different release kinetics. The difference in the drug release is probably due to the difference in the drug dissolution within the core, before its partition and diffusion through the CaPG coat. The CAF dissolved faster and achieved a higher concentration in solution, which drove diffusion. The release of TBR from the coated pellets was much slower than that of the CAF or TPL because of its low solubility. However, the release of all drugs was about four- to sixfold slower for coated than uncoated pellets, suggesting that the coating influenced the retardation of drug release from the coated pellets. Therefore, the CaPG coating may provide a sustained release delivery system for all drugs tested.
Publisher: Elsevier BV
Date: 07-2021
Publisher: Elsevier BV
Date: 12-2006
DOI: 10.1016/J.IJPHARM.2006.07.004
Abstract: Spherical pellets containing theophylline, calcium acetate and microcrystalline cellulose were extruded and spheronized, before being coated with six different pectins or alginates by interfacial complexation. The aim of this study was to discover the effect of the coatings on physico-mechanical properties that will be crucial in determining the pellets' utility as sustained release systems. An insoluble, smooth and uniformly thick coat of calcium polysaccharide was formed around the core pellets. A factorial experiment was designed to investigate the effect of pellet size and polysaccharide type and concentration on the entrapment efficiency, mechanical properties and other physical characteristics. Coated pellets were observed by scanning electron microscopy and, depending on the particular polysaccharide used, the dry coats were found to be 30-80 microm thick. The size of pellet, the type and concentration of polysaccharide influenced the yield of theophylline in the coated pellets. Although the mechanical properties of the pellets were improved by applying any of the gel coats, use of an alginate with a high content of guluronic acid or an amidated pectin coating gave the best results. This is probably because both of these have significant potential to form very stable cross-links within the gel coats.
Publisher: Informa UK Limited
Date: 2003
Abstract: Combinations of Eudragit RS and deesterified pectin, polygalacturonic acid (PGA), or its potassium and sodium salts, when applied as a film coat, has a potential value as a colon-specific delivery system. Dispersions of PGA in Eudragit RS were used as the film former for coating of 5-aminosalicylic acid (5-ASA) tablet cores. Drug release behavior was assessed, in vitro, under simulating conditions in term of pH and time to in vivo during their transit to the colon. Negligible drug release occurred during first 5 hr where the coated tablets were in the stomach and small intestine. After that, the pectinolytic enzymes were added into the pH 6.8 medium to simulate the in vivo condition where there is the digestion of bacteria in the colon. The release of 5-ASA from the coated tablets occurred linearly as a function of time. Drug release depended on the composition of the mixed film, as well as the ratio of Eudragit RS to PGA or its salts. The highest drug release from the coated tablets of about 40% was obtained when the ratio of Eudragit RS to potassium salt of PGA was 2.5 to 1. Drug release profiles seemed to conform to the mechanism involving the osmotically driven release and formation of channels in the film caused by dissolution of PGA salts. Channel formation was, in most cases, activated by the presence of pectinolytic enzymes, showing that the PGA in the mixed film was subjected to enzymic breakdown. In conclusion, PGA could be used as an additive in Eudragit RS films to control the release of colonic delivery system.
Publisher: Trans Tech Publications, Ltd.
Date: 04-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.506.35
Abstract: The effect of physical aging on the properties of starch is important to understand structural relaxation and to control the physicochemical changes after pregelatinization which induced by aging. In this study, the effect of physical aging on the physicochemical properties of pregelatinized tapioca starch was investigated. The tapioca starch was pregelatinized by either heating at 80°C or using high power (400 W) ultrasonic treatment. After pregelatinization, dextrose equivalent (DE), viscosity, turbidity, swelling power and solubility were determined and compared with native tapioca starch. Compared to fresh tapioca starch, the aged starch exhibited an increase in DE, turbidity and solubility. The viscosity and swelling power were decreased after storage. Similar results were found for both tapioca starches pregelatinized by heat and ultrasonic treatments. The results of the physicochemical properties of pregelatinized starches obtained from ultrasonic treatment related to the formation of low molecular weight components that aging starch are easily changed by disruption of molecular structure within the starch granule.
Publisher: Elsevier BV
Date: 10-2016
Publisher: Trans Tech Publications, Ltd.
Date: 06-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.970.272
Abstract: This work has a focus on the self-emulsifying drug delivery system (SEDDS), which can be used in pharmaceutical field for increasing bioavailability of poorly water-soluble drugs. The model drug resveratrol was used because of its poor water-solubility and is of interest because of its wide range of pharmacological effects. It is beneficial to understand the mechanism of SEDDS formation in the human body, therefore, the determination of nanoscale structure was carried out. For this purpose, small angle X-ray scattering (SAXS), photon correlation spectroscopy (PCS), and transmission electron microscopy (TEM) techniques were applied. We have found that the size and size distribution of particles were in nanometers. The inner structure of SEDDS was ordered with the lamellar distances (d-spacing) of 20 nm. It seems that the prepared SEDDS in water form large oil drops (200-400 nm) in water as well as small micelles with the droplet size of 10-20 nm.
Publisher: Springer Science and Business Media LLC
Date: 16-05-2022
DOI: 10.1186/S12913-022-08021-2
Abstract: Health care incidents, such as medical errors, cause tragedies all over the world. Recent legislation in the Netherlands has established medical dispute committees to provide for an appeals procedure offering an alternative to civil litigation and to meet the needs of clients. Dispute committees incorporate a hybrid procedure where one can file a complaint and a claim for damages resulting in a verdict without going to court. The procedure is at the crossroads of complaints law and civil litigation. This study seeks to analyze to what extent patients and family members’ expectations and experiences with dispute committees match the goals of the new legislation. This qualitative, retrospective research includes in-depth, semi-structured, face-to-face interviews with patients or family members who filed a complaint with a dispute committee in the Netherlands. The researchers conducted an inductive, thematic analysis of the qualitative data. A total of 26 interviews were held with 30 patients and family members. The results showed that participants particularly felt the need to be heard and to make a positive impact on health care. Some wished to be financially compensated, for others money was the last thing on their mind. The results demonstrated the existence of unequal power relationships between participants and both the defendant and dispute committee members. Participants reported the added value of (legal) support and expressed the need for dialogue at the hearing. Participants sometimes experienced closure after the proceedings, but often did not feel heard or felt a lack of a practical outcome and a tangible improvement. This study shows that participants’ expectations and experiences were not always met by the current set up of the dispute committee proceedings. Participants did not feel heard, while they did value the potential for monetary compensation. In addition, some participants did not experience an empowered position but rather a feeling of a power misbalance. The feeling of a power misbalance and not being heard might be explained by existing epistemic injustice, which is a concept that should be carefully considered in processes after health care incidents.
Publisher: Springer Science and Business Media LLC
Date: 06-07-2021
DOI: 10.1007/S13246-021-01031-0
Abstract: The introduction of MRI linear accelerators (MR-linacs) and the increased use of MR imaging in radiotherapy, requires improved approaches to MRI-only radiotherapy. MRI provides excellent soft tissue visualisation but does not provide any electron density information required for radiotherapy dose calculation, instead MRI is registered to CT images to enable dose calculations. MRI-only radiotherapy eliminates registration errors and reduces patient discomfort, workload and cost. Electron density requirements may be addressed in different ways, from manually applying bulk density corrections, to more computationally intensive methods to produce substitute CT datasets (sCT), requiring additional sequences, increasing overall imaging time. Reducing MR imaging time would reduce potential artefacts from intrafraction motion and patient discomfort. The aim of this study was to assess the impact of reducing MR imaging time on a hybrid atlas-voxel sCT conversion for prostate MRI-only treatment planning, considering both anatomical and dosimetric parameters. 10 volunteers were scanned on a Siemens Skyra 3T MRI. Sequences included the 3D T2-weighted (T2-w) SPACE sequence used for sCT conversion as previously validated against CT, along with variations to this sequence in repetition time (TR), turbo factor, and combinations of these to reduce the imaging time. All scans were converted to sCT and were compared to the sCT from the original SPACE sequence, evaluating for anatomical changes and dosimetric differences for a standard prostate VMAT plan. Compared to the previously validated T2-w SPACE sequence, scan times were reduced by up to 80%. The external volume and bony anatomy were compared, with all but one sequence meeting a DICE coefficient of 0.9 or better, with the largest variations occurring at the edges of the external body volume. The generated sCT agreed with the gold standard sCT within an isocentre dose of 1% and a gamma pass rate of 99% for a 1%/1 mm gamma tolerance for all but one sequence. This study demonstrates that the MR imaging sequence time was able to be reduced by approximately 80% with similar dosimetric results.
Publisher: Trans Tech Publications, Ltd.
Date: 12-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.1060.176
Abstract: Binary solid dispersions of manidipine hydrochloride (MDP) and polyethylene glycol (PEG) 4000 are prepared by melting method. Drug loading and process temperature are varied in the range of 5-30% and 150-210°C, respectively. After melting, only the formulation using 5% MDP and process temperature of 210°C showed yellow clear solution and halo pattern of powder X-ray diffractograms with the absence of peaks. These results indicated that the higher process temperature (210°C) can melt all MDP powders and provide the amorphous product. Moreover, only the higher carrier content can change the crystalline form of MDP to the amorphous form. A clear, solid solution could not be prepared when the drug loading was higher than 5%. In this study, the melting technique avoiding the use of organic solvent was successfully applied to prepared binary solid dispersion.
Publisher: IOP Publishing
Date: 28-04-2022
Abstract: Objective. Reference dosimetry on an MRI-linac requires a chamber specific magnetic field correction factor, k B ⃗ . This work aims to measure the correction factor for a parallel plate chamber on a parallel MRI-linac. Approach. k B ⃗ is defined as the ratio of the absorbed dose to water calibration coefficient in the presence of the magnetic field, N D , w B ⃗ relative to that under 0 T conditions, N D , w 0 T . k B ⃗ was measured via a N D , w transfer to a field chamber at each magnetic field strength from a chamber with known N D , w and k B ⃗ . This was achieved on the parallel MRI-linac by moving the measurement set-up between a high magnetic field strength region at the MRI-isocentre and a low magnetic field strength region at the end of the bore whilst maintaining consistent set-up and scatter conditions. Three PTW 34001 Roos chambers were investigated as well as a PTW 30013 Farmer used to validate methodology. Main Results. The beam quality used for the measurements of k B ⃗ was TPR 20 / 10 = 0.632. The k B ⃗ for the PTW Farmer chamber at 1 T on a parallel MRI-linac was 0.993 ± 0.013 ( k = 1). The average k B ⃗ factor measured for the three Roos chambers on a 1 T parallel MRI-linac was 0.999 ± 0.014 ( k = 1). Significance. The results presented are the first measurements of k B ⃗ for a Roos chamber on a parallel MRI-linac. The Roos chamber results demonstrate the potential for the chamber as a reference dosimeter in parallel MRI-linacs.
Publisher: MDPI AG
Date: 05-08-2021
DOI: 10.3390/GELS7030108
Abstract: Dysphagia refers to difficulty swallowing certain foods, liquids, or pills. It is common among the elderly with chronic diseases who need to take drugs for long periods. Therefore, dysphagia might reduce compliance with oral drug administration in the aging population. Many pharmaceutical companies search for new products to serve as swallowing aids. Existing products are expensive and do not suit all geriatric patients. Therefore, this study aimed to develop and investigate pill swallowing aid gels prepared from carboxymethyl cellulose and chitosan. We formulated gels by dissolving different concentrations of carboxymethyl cellulose and low or high molecular weight chitosan in solvents to find appropriate gel rheology properties. We then added several portions of glycerin as the glidant of the formulation. We found that the optimized gel formulation was 6.25% (w/w) chitosan with a molecular weight of 80–120 kDa dissolved in 1.2% acetic acid and 4% (w/w) glycerin. The developed pill swallowing gel’s rheology was pseudoplastic with a viscosity of 73.74 ± 3.20 Pa⸱s. The developed chitosan gel had enhanced flow ability it allowed the pill to cross a 300 mm tube within 6 s, while the reference product took 3 s. Even though the reference product could carry the pill in the tube faster, the chitosan gel better covered the pill, making it more convenient to use. Finally, using a theophylline tablet as a model tablet dosage form, we assessed the gel’s effect on drug disintegration and dissolution. The chitosan gel delayed the tablet disintegration time by about 3–7 min and slightly affected the theophylline dissolution rate. Lastly, all gels were physically stable after a month of storage in the stress condition. These results show the feasibility of manufacturing a chitosan gel usable as a pill swallowing gel for patients with dysphagia.
Publisher: Elsevier BV
Date: 03-2008
DOI: 10.1016/J.IJPHARM.2007.10.038
Abstract: Understanding the gel ultrastructure is of great importance for process and product development having great effects on the product characteristics. The s les containing high amount of water could not be directly observed using scanning electron microscope (SEM) without removing of water. However, cryo-SEM can be used to study the ultrastructure of hydrated s les. In this study, ultrastructural information of internal structure was obtained by imaging the cryo-fractured beads in a cryo-SEM. This technique was found to be excellent for studying the detailed morphology of structural development and showed better images than normal SEM procedures using freeze-drying for s le preparation. Also, the studies illustrated a morphological change, e.g. from net-like structure to membranous structure caused by syneresis, accompanied by a significant increase in mechanical properties, when the beads are formed by ionotropic gelation. The gelation time of 20 min was found to be the minimum for a complete bead formation, based on the mechanical and SEM data. The results demonstrate the advantageous of cryo-SEM for examining the ultrastructure during bead formation of calcium pectinate.
Publisher: Elsevier BV
Date: 07-2021
Publisher: Elsevier BV
Date: 09-2004
Publisher: Springer Science and Business Media LLC
Date: 20-02-2023
DOI: 10.1007/S13246-023-01223-W
Abstract: Consistency and clear guidelines on dosimetry are essential for accurate and precise dosimetry, to ensure the best patient outcomes and to allow direct dose comparison across different centres. Magnetic Resonance Imaging Linac (MRI-linac) systems have recently been introduced to Australasian clinics. This report provides recommendations on reference dosimetry measurements for MRI-linacs on behalf of the Australiasian College of Physical Scientists and Engineers in Medicine (ACPSEM) MRI-linac working group. There are two configurations considered for MRI-linacs, perpendicular and parallel, referring to the relative direction of the magnetic field and radiation beam, with different impacts on dose deposition in a medium. These recommendations focus on ion chambers which are most commonly used in the clinic for reference dosimetry. Water phantoms must be MR safe or conditional and practical limitations on phantom set-up must be considered. Solid phantoms are not advised for reference dosimetry. For reference dosimetry, IAEA TRS-398 recommendations cannot be followed completely due to physical differences between conventional linac and MRI-linac systems. Manufacturers’ advice on reference conditions should be followed. Beam quality specification of TPR 20,10 is recommended. The configuration of the central axis of the ion chamber relative to the magnetic field and radiation beam impacts the chamber response and must be considered carefully. Recommended corrections to delivered dose are $${k}_{{Q}_{msr}{Q}_{0}}^{{f}_{msr}{f}_{ref}}$$ k Q msr Q 0 f msr f ref , a correction for beam quality and $${k}_{\\overrightarrow{B},{Q}_{msr}}^{{f}_{msr}}$$ k B → , Q msr f msr , for the impact of the magnetic field on dosimeter response in the magnetic field. Literature based values for $${k}_{\\overrightarrow{B},{Q}_{msr}}^{{f}_{msr}}$$ k B → , Q msr f msr are given. It is important to note that this is a developing field and these recommendations should be used together with a review of current literature.
Publisher: Elsevier BV
Date: 2010
Publisher: Elsevier BV
Date: 09-1997
Publisher: Elsevier BV
Date: 04-2011
Publisher: Elsevier BV
Date: 06-2007
DOI: 10.1016/J.EJPB.2006.12.003
Abstract: Hydrophilic matrix tablets based on the alginate system have been used in relation to their possible function in modified drug delivery formulations using metronidazole as a model drug. The matrix tablets were prepared by direct compression using different grades of alginate. The effect of some factors (i.e. particle size of drug, additive used, and pH of medium) on drug release from alginate-based matrix tablets was also investigated. Swelling, erosion, and in vitro release studies of the matrix tablets were carried out in 0.1N HCl or phosphate buffer (pH 6.8). The alginate-based matrix tablets swelled or eroded while in contact with the aqueous medium and formed a continuous gel layer or underwent combination of swelling and erosion. The swelling action of alginate matrices is controlled by the rate of its hydration in the medium. Different grades of alginate insignificantly influenced the matrix swelling in acidic medium but significantly influenced in neutral medium. The presence of ammonium or calcium salts induced tablet disintegration in acidic medium. However, incorporation of calcium acetate and sodium bicarbonate can alter the tablet swelling in acidic medium. Release studies showed that all investigated factors influence the drug release. The extent of matrix swelling, erosion, and diffusion of drug determined the kinetics as well as mechanism of drug release from alginate-based matrix tablets. Most of the release data in acidic medium showed a good fit into Korsmeyer-Peppas equation but fitted well with zero-order release model, in neutral medium.
Publisher: MDPI AG
Date: 04-07-2023
DOI: 10.3390/PHARMACEUTICS15071877
Abstract: Three-dimensional (3D) printing is an unrivaled technique that uses computer-aided design and programming to create 3D products by stacking materials on a substrate. Today, 3D printing technology is used in the whole drug development process, from preclinical research to clinical trials to frontline medical treatment. From 2009 to 2020, the number of research articles on 3D printing in healthcare applications surged from around 10 to 2000. Three-dimensional printing technology has been applied to several kinds of drug delivery systems, such as oral controlled release systems, micropills, microchips, implants, microneedles, rapid dissolving tablets, and multiphase release dosage forms. Compared with conventional manufacturing methods of pharmaceutical products, 3D printing has many advantages, including high production rates due to the flexible operating systems and high drug loading with the desired precision and accuracy for potent drugs administered in small doses. The cost of production via 3D printing can be decreased by reducing material wastage, and the process can be adapted to multiple classes of pharmaceutically active ingredients, including those with poor solubility. Although several studies have addressed the benefits of 3D printing technology, hospitals and pharmacies have only implemented this process for a small number of practical applications. This article discusses recent 3D printing applications in hospitals and pharmacies for medicinal preparation. The article also covers the potential future applications of 3D printing in pharmaceuticals.
Publisher: Trans Tech Publications, Ltd.
Date: 04-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.506.282
Abstract: The aim of this study was to develop the pectin-based microparticles by emulsion-solvent evaporation technique. The effects of concentration and type of pectin and addition of glutaraldehyde on size, size distribution, drug crystalline state and drug dissolution from microparticles were investigated. The results showed that a model drug, indomethacin, could be encapsulated in microparticles. Higher molecular weight of pectin caused a larger in size of microparticles than the lower one. A high degree of esterification is preferred to stabilize the pectin microparticles. The powder x-ray diffractograms showed that all microparticles led to amorphous products while their physical mixture still showed the crystalline state of drug. Drug dissolution from the microparticles containing indomethacin and pectin was increased, resulting from the formation of an amorphous solid dispersion. Addition of glutaraldehyde, however, resulted in slower drug dissolution, compared to the formulations without glutaraldehyde or drug alone.
Publisher: Trans Tech Publications, Ltd.
Date: 12-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.1060.145
Abstract: The aim of the study was to develop neural network model to predict the yield obtained from ultrasound-assisted anti-solvent crystallization of ibuprofen in terms of formulation and processing factors. The different factors of anti-solvent crystallization method, such as type of additive, concentration of additive, sonication time and harvesting time, were used as independent variables. The ibuprofen yield was used as response variable. The correlation between independent and response variables was investigated using feed forward-back propagation neural networks. The goodness of fit test and predictability were used for optimization of in silico models. The results revealed that the type of polyethylene glycol (PEG) was a critical factor that affected the response variable in different patterns. The best artificial neural networks (ANNs) model with a configuration of 3-4-1 for input, hidden, and output layers gave the r 2 of 0.7067 and 0.8729 and the root mean square error of 0.3693 and 0.2667 for the model using PEG 400 and PEG 4000, respectively. The predictive ability of these models was validated by a set of 4 formulations that were not included in the training set. The predicted and experimental of ibuprofen yields were correlated.
Publisher: Trans Tech Publications, Ltd.
Date: 04-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.506.286
Abstract: Pectin-based nanoemulsions loaded with itraconazole were prepared using high-pressure homogenizer comparing to sonicator. The high-pressure homogenization provided the smaller size of emulsions when homogenizing time was increased. Using the homogenizing pressure of 100 MPa for 90 minutes could provide nanosized emulsions. Sonication method could reduce the emulsion size, however, the size was limited to approximately 2 µm. The type of pectin also influenced the emulsion size. Using high methoxyl pectin (HMP) provided the smallest emulsion, compared to low methoxyl pectin (LMP) and amidated low methoxyl pectin (ALMP). This may be due to the high portion of hydrophobic moieties of HMP which provides better emulsifying properties. From these results, the high-pressure homogenization could produce the nanosized emulsions. Pectin type significantly influenced the emulsion properties. Therefore, the use of high-pressure homogenization method with the proper emulsifiers could provide the nanosized emulsions.
Publisher: Informa UK Limited
Date: 2002
Abstract: The effect of heat on the characteristics of chitosan film coated on theophylline tablets was studied. Chitosan of high viscosity grade with molecular weight in the range of 800,000-1,000,000, 80-85% degree of deacetylation was used as a film former by dissolving in 1% v/v acetic acid solution. The coated tablets had been cured at 40, 60, and 100 degrees C for 6, 12, and 24 hr. The morphology of the film at the edge and surface of coated tablets was investigated using scanning electron microscopy. Film cracking was increased and clearly observed in the coated tablets cured at 100 degrees C for 24 hr. As a result, more water could be absorbed into the tablets, followed by faster disintegration and faster drug release. The evidence of partial conversion of chitosonium acetate to chitin in the 13C nuclear magnetic resonance (NMR) spectra of chitosan films cured at 40, 60, and 100 degrees C was observed, but it had no effect on drug release behavior. Theophylline tablets coated with chitosan films gave sustained release behavior in various media, i.e., distilled water, 0.1 N hydrochloric acid, pH 4.5 acetate buffer, and pH 6.8 phosphate buffer. In addition, the film coating temperature at 55-60 degrees C and curing process at 40 and 60 degrees C had no effect on the drug release from theophylline tablets coated with chitosan polymer. Finally, it might be concluded that both the physical and chemical properties of chitosan films were affected by heat.
Publisher: Elsevier BV
Date: 06-2021
Publisher: Springer Science and Business Media LLC
Date: 05-05-2010
Publisher: Elsevier BV
Date: 08-2008
DOI: 10.1016/J.EJPB.2008.01.027
Abstract: A new oral-controlled release matrix tablet based on shellac polymer was designed and developed, using metronidazole (MZ) as a model drug. The shellac-based matrix tablets were prepared by wet granulation using different amounts of shellac and lactose. The effect of annealing temperature and pH of medium on drug release from matrix tablets was investigated. The increased amount of shellac and increased annealing temperature significantly affected the physical properties (i.e., tablet hardness and tablet disintegration) and MZ release from the matrix tablets. The in-situ polymerization played a major role on the changes in shellac properties during annealing process. Though the shellac did not dissolve in acid medium, the MZ release in 0.1N HCl was faster than in pH 7.3 buffer, resulting from a higher solubility of MZ in acid medium. The modulation of MZ release kinetics from shellac-based matrix tablets could be accomplished by varying the amount of shellac or annealing temperature. The release kinetics was shifted from relaxation-controlled release to diffusion-controlled release when the amount of shellac or the annealing temperature was increased.
Publisher: Elsevier BV
Date: 02-2007
Publisher: Trans Tech Publications, Ltd.
Date: 08-2013
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.747.162
Abstract: Nanoparticulate system composing of polymeric or lipid materials have been proposed as drug carriers for improving efficacy of encapsulated drugs. Different materials, e.g. phospholipids and polysaccharides, have been proposed for the production of these systems due to their biocompatibility, biodegradability, low cost and safety. In this study, we report a novel particulate system containing lecithin-pectin complexes loaded with a lipophilic drug, itraconazole. The effect of pectin concentration on particle formation and drug dissolution was also investigated. The lecithin-pectin complexes were prepared by thin film method using soya lecithin and then hydrated with different concentration of pectin solution. The surface charge (zeta potential) and particle size of complex particles were characterized. The drug dissolution was determined by using USP dissolution apparatus. The results demonstrated that the particle size of complex particles were in nanometer range. When concentration of pectin increased, the size increased slightly while the surface charge of complex particles was less negative. The drug dissolution from complex particles containing lecithin and pectin was higher than those containing only pectin.
Publisher: Informa UK Limited
Date: 05-2005
Publisher: Elsevier BV
Date: 05-2017
Publisher: Elsevier BV
Date: 12-2020
Publisher: Elsevier BV
Date: 15-07-1998
Publisher: Elsevier BV
Date: 03-2005
DOI: 10.1016/J.EJPS.2004.12.004
Abstract: Emulsion gel (EMG) beads of calcium pectinate capable of floating in the gastric condition were developed using an emulsion-gelation method and their release properties were investigated. Attempts to modify the drug release were made by applying some additives into the starting solution prior to bead formation, by hardening with glutaraldehyde, and by coating with polymer. The metronidazole-loaded EMG beads were found to float on simulated gastric fluid. Increasing the drug to pectin ratio in the beads slowed the drug release from the conventional and the EMG beads. However, the drug release from these beads was rapid, i.e., about 80% of drug loading released within 20-80 min. The additives (PEG10000, glyceryl monostearate and Eudragit L) had a slight, insignificant, effect on the drug release. Using 2% glutaraldehyde as a hardening agent prolonged the drug release. Coating the beads with Eudragit RL significantly sustained the drug release while the beads remained buoyant. The results suggest that EMG beads are suitable as a carrier for intragastric floating drug delivery and that their release behaviour could be modified by hardening with glutaraldehyde or by coating with Eudragit RL.
Publisher: Elsevier BV
Date: 07-2018
DOI: 10.1016/J.IJPHARM.2018.04.052
Abstract: The objective of this study was to investigate the in vitro cytotoxicity and in vivo anticancer efficacy of redox-responsive microbeads containing thiolated pectin-doxorubicin (DOX) conjugate. Oral microbeads were coated with an enteric polymer to protect the drug from release in the upper gastrointestinal (GI) tract and allow redox-triggered drug release in the colon. Morphology, particle size, drug content, and in vitro drug release behavior of the microbeads were characterized in vitro cytotoxicity was tested on mouse colon carcinoma, human colorectal adenocarcinoma, and human bone osteosarcoma cell lines. In vivo anticancer efficacy of coated microbeads was examined in BALB/c mice with murine colon carcinoma. These coated microbeads significantly inhibited the growth of all cell lines. The in vivo study confirmed delivery of DOX to the colorectal tumor site, redox-responsiveness, and anticancer efficacy of coated microbeads. Coated microbeads also effectively inhibited primary tumor growth and suppressed tumor metastases without gross toxicity to the non-target tissue. No noticeable damage was found in mouse GI tissues, indicating lack of DOX toxicity. These novel coated microbeads containing thiolated pectin-DOX conjugate may be a promising vehicle for targeted clinical delivery of DOX to the colorectal cancer site by oral administration.
Publisher: MDPI AG
Date: 09-07-2021
DOI: 10.3390/PHARMACEUTICS13071046
Abstract: The objective of this research was to optimize the tasted-masked microparticles for orally disintegrating tablets containing donepezil hydrochloride using quality risk assessment and design of experiment approaches. The double emulsion solvent evaporation technique using aminoalkyl methacrylate copolymer (AMC) was used to prepare taste-masked microparticles. Factors affecting the quality of the taste-masked microparticles were analyzed using an Ishikawa diagram. A risk-ranking approach was used to rank the formulation and process risks. Furthermore, the effect of AMC quantity, stirring time, and volume of outer water phase on various responses, such as particle size, the amount of drug dissolved at 5 min (Q5) in simulated saliva fluid, and mean dissolution time (MDT) in simulated gastric fluid, was investigated using the Box-Behnken design. The optimized microparticles were then used to prepare orally disintegrating tablets (ODTs) and evaluated by in vitro and in vivo testing. The results demonstrated that particle size was influenced by the AMC amount and stirring time. Q5 was significantly affected by the amount of AMC and the volume of the outer water phase. On the other hand, these two factors had a positive effect on MDT. The optimized microparticles had a particle size of 174.45 ± 18.19 µm, Q5 of 5.04%, and MDT of 5.97 min. The ODTs with taste-masked microparticles showed acceptable in vitro dissolution with an MDT of 5 min. According to the results of a panel of six human volunteers, they greatly improved palatability.
Publisher: Trans Tech Publications, Ltd.
Date: 04-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.506.290
Abstract: The objective of this study was to explore the effect of clay on mechanical and related properties of shellac (SHL) films. The SHL was dissolved in ammonia solution, and then casted into the film. For SHL-clay composite film, bentonite (BTN) which is popular clay in pharmaceuticals, was added and well dispersed before casting. The SHL and SHL-BTN composite films were then comparatively characterized. The results showed that SHL-BTN composite films were stiffer than SHL films since the modulus was 3 times higher. However, the percent elongation was lower, suggesting the more fragility of composite film. The drawback of composite film was solved by adding of polyethylene glycol. The percent elongation of composite film, puncture strength and modulus were higher than those of SHL film. However, BTN may be dispersed in the film without any interaction of shellac molecules since the FTIR spectrum of SHL-BTN composite film did not change as compared to physical mixture of SHL and BTN. The knowledge gained should provide an alternative way of modification of shellac properties for coating.
Publisher: Elsevier BV
Date: 10-1997
Publisher: Trans Tech Publications, Ltd.
Date: 04-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.506.294
Abstract: A new processing method for the production of modified starch, high power ultrasonic treatment (400 W), was applied to native tapioca starch. The effect of processing parameters such as ultrasound litude (50 and 100%) and sonication time (10, 20 and 30 minutes) on the properties of the modified starches was investigated. Starch granule morphology observed by scanning electron microscopy (SEM), swelling power, solubility and powder x-ray diffractometry (PXRD) of the obtained ultrasonically treated tapioca starch were determined and compared with native as well as heat-treated tapioca starches. The results from SEM and PXRD showed that the ultrasonic treatment of tapioca starch distorted the crystalline region in starch granules, especially at higher litude or sonication time. The swelling power of the tapioca starch increased after treatment with both heat and ultrasound, in which the swelling power of ultrasonically treated starch was higher than that of heat-treated starch. It was found that tapioca starch treated by ultrasound for a certain period of time has an increase in solubility. The increase in the swelling power is associated with water absorption capacity and starch granules solubility.
Publisher: Trans Tech Publications, Ltd.
Date: 12-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.1060.155
Abstract: The aim of this study was to compare the in vitro binding of bile salts by coconut fiber, a by-product of coconut milk extraction. The raw coconut fiber was processed by different methods before binding test, that is, sieving, pulverizing in mortar, grinding by a dry grinder, digesting with 0.1 N hydrochloric acid (HCl), grinding by a dry grinder and then digesting with 0.1 N HCl. The resultant coconut fiber was sieved to obtain the particle size ranged from 250 to 600 μm. Various bile salts, i.e., sodium deoxycholate, sodium cholate and sodium taurocholate, were in idually tested and analyzed by high performance liquid chromatography. The results showed that sodium deoxycholate was bound by sieved coconut fiber (9.64%), mortar-ground coconut fiber (12.91%), grinder-ground coconut fiber (28.31%), acid-digested coconut fiber (41.14%), and grinder-ground and acid-digested coconut fiber (37.54%). Similar results were obtained when sodium cholate and sodium taurocholate were tested but to a lesser extent. It can be concluded from these results that coconut fiber may have potential application as a cholesterol-reducing agent.
Publisher: Trans Tech Publications, Ltd.
Date: 08-2011
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.311-313.1140
Abstract: Floating matrix tablets were designed and evaluated. Theophylline was used as a model drug. The system was prepared by mixing drug, matrix-forming polymer (hydroxypropyl methylcellulose, HPMC) and fillers together. The blended powder was compressed by hydraulic press. The effect of formulation variables such as type of matrix forming polymer (HPMC K100LV, HPMC K4M, HPMC K100M), amount of effervescent agent (0, 20, 30, 40% w/w) and compression force (0.5, 1 ton) on floating properties and drug release of floating matrix tablets were investigated. The results demonstrated that type of polymer affected floating properties of the floating matrix tablets. The floating matrix tablets prepared from lower viscosity HPMC (HPMC K100LV) showed faster drug release than those prepared from higher viscosity HPMC (HPMC K4M, HPMC K100M). Increasing amount of effervescent agent decreased time to float and increased drug release from the floating matrix tablets. Higher compression force did not affect time to float but decreased drug release from the floating matrix tablets. According to these results, floating properties and drug release of the floating matrix tablets could be modified by formulation variables. Some floating tablet formulations developed in this study showed good floating properties (time to float less than 15 minutes, floating time more than 8 hours) with sustained release as required. The system is promising as a carrier for gastroretentive drug delivery systems.
Publisher: Trans Tech Publications, Ltd.
Date: 08-2013
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.747.725
Abstract: The aim of study was to prepare a water compatible form of soybean oil through nanoemulsification. Factors affecting properties of nanoemulsions containing soybean oil such as types and amounts of surfactants (Tween 60, Cremophor RH-40, sodium lauryl sulfate (SLS) and Lutrol F-127) were investigated. The results demonstrated that types and amount of surfactants affected the formation and physical stability of nanoemulsions. The emulsions containing Cremophor RH-40 and Lutrol F-127 showed 100% creaming while those containing Tween 60 and SLS indicated the lower percentage of creaming suggesting the less physical stability. However, the formation of nanoemulsions was not observed in the formula containing Lutrol F-127. The average droplet size of emulsions was 1766 nm and 193 nm for emulsions containing 5% w/w Lutrol F-127 and Cremophor RH-40, respectively. The droplet size was also affected by the amount of Cremophor RH-40. The droplet size was decreased from 795 to 114 nm as increasing amount of Cremophor RH-40 from 2.5 to 10 %w/w. Additionally, the properties of nanoemulsions containing Cremophor RH-40, including physical appearance, droplet size and zeta potential, were not change even after temperature cycling. In conclusion, the more water compatible form of soybean oil was accomplished through incorporation into the nanoemulsions with specific type and amount of surfactant.
Publisher: Trans Tech Publications, Ltd.
Date: 10-2011
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.152-153.1700
Abstract: The objective of this study was to model the drug release property in terms of process variables of microwave-assisted modification of arrowroot starch using artificial neural network (ANN). The water content, microwave power and heating time were used as process variables for modification of arrowroot starch and the mean dissolution time was used as dependent variable. The correlation between process variables and dependent variable was examined using feed-forward back-propagation neural networks. The ANN model was optimized by considering goodness-of-fit and crossvalidated predictability. A “leave-one-out” cross-validation revealed that the neural network model could predict MDT values from matrix tablets with a reasonable accuracy (predictive r2 of 0.824 and predictive root mean square error of 19.53). The predictive ability of these models was validated by a set of 4 formulations that were not included in the training set. The predicted and observed MDT were well correlated.
Publisher: Trans Tech Publications, Ltd.
Date: 12-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.1060.151
Abstract: Solvent miscibility is an important parameter for dosage form design, especially for liquid preparations. The purpose of this study was to investigate the polarity change of coconut oil (CO) after modification by glycerolysis and its consequence on solvent miscibility. Coconut oil and its modified form were separately mixed with various solvents which had different dielectric constant and then determined for their miscibility. The thin layer chromatography (TLC) was also used to clarify the composition of coconut oil and its modified form. The result indicated that coconut oil and modified coconut oil (MCO) were miscible with low polarity solvent having the dielectric constant from 1.94 to 21.5 (from hexane to acetone) and were immiscible with high polarity solvents possessing the dielectric constant over 42.5. However, MCO demonstrated miscibility with ethanol, propylene glycol and methanol (dielectric constant 24.5, 32.1, 32.7) while coconut oil did not compatible with those solvents. The result suggested the polarity increment of MCO after glycerolysis. The presence of high polar compounds, including monolaurin and lauric acid in MCO was later clarified by TLC. In conclusion, the knowledge gained from this research may provide the preliminary data for formulation of MCO into suitable liquid dosage form in the near future.
Publisher: Wiley
Date: 09-2004
Location: Netherlands
No related grants have been discovered for Antony Pemberton.