ORCID Profile
0000-0003-3850-1778
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Curtin University
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Publisher: American Society for Microbiology
Date: 2014
DOI: 10.1128/AAC.01437-13
Abstract: Since conventional 14-day primaquine (PMQ) radical cure of vivax malaria is associated with poor compliance, and as total dose, not therapy duration, determines efficacy, a preliminary pharmacokinetic study of two doses (0.5 and 1.0 mg/kg of body weight) was conducted in 28 healthy glucose-6-phosphate dehydrogenase-normal Papua New Guinean children, aged 5 to 12 years, to facilitate development of abbreviated high-dose regimens. Dosing was with food and was directly observed, and venous blood s les were drawn during a 168-h postdose period. Detailed safety monitoring was performed for hepatorenal function and hemoglobin and methemoglobin concentrations. Plasma concentrations of PMQ and its metabolite carboxyprimaquine (CPMQ) were determined by liquid chromatography-mass spectrometry and analyzed using population pharmacokinetic methods. The derived models were used in simulations. Both single-dose regimens were well tolerated with no changes in safety parameters. The mean PMQ central volume of distribution and clearance relative to bioavailability (200 liters/70 kg and 24.6 liters/h/70 kg) were within published ranges for adults. The median predicted maximal concentrations ( C max ) for both PMQ and CPMQ after the last dose of a 1.0 mg/kg 7-day PMQ regimen were approximately double those at the end of 14 days of 0.5 mg/kg daily, while a regimen of 1.0 mg/kg twice daily resulted in a 2.38 and 3.33 times higher C max for PMQ and CPMQ, respectively. All predicted median C max concentrations were within ranges for adult high-dose studies that also showed acceptable safety and tolerability. The present pharmacokinetic data, the first for PMQ in children, show that further studies of abbreviated high-dose regimens are feasible in this age group.
Publisher: American Society for Microbiology
Date: 2001
DOI: 10.1128/AAC.45.1.181-186.2001
Abstract: To provide novel data relating to the dispositions, effects, and toxicities of the artemisinin derivatives in severe malaria, we studied 30 Vietnamese adults with slide-positive falciparum malaria treated with intravenous artesunate. Twelve patients with complications (severe group 1) and 8 patients without complications but requiring parenteral therapy (moderately severe group 2) received 120 mg of artesunate by injection, and 10 patients with moderately severe complications (group 3) were given 240 mg by infusion. Serial concentrations of artesunate and its active metabolite dihydroartemisinin in plasma were measured by high-performance liquid chromatography. The time to 50% parasite clearance (PCT 50 ) was determined from serial parasite densities. Full clinical (including neurological) assessments were performed at least daily. In noncompartmental pharmacokinetic analyses, group mean artesunate half-lives ( t 1/2 ) were short (range, 2.3 to 4.3 min). The dihydroartemisinin t 1/2 (range, 40 to 64 min), clearance (range, 0.73 to 1.01 liters/h/kg), and volume of distribution (range, 0.77 to 1.01 liters/kg) were also similar both across the three patient groups ( P 0.1) and to previously reported values for patients with uncomplicated malaria. Parasite clearance was prompt (group median PCT 50 range 6 to 9 h) and clinical recovery was complete under all three regimens. These data indicate that the pharmacokinetics of artesunate and dihydroartemisinin are not influenced by the severity of malaria. Since the pharmacokinetic parameters for both artesunate and dihydroartemisinin were similar regardless of whether injection or infusion was used, artesunate can be considered a prodrug that is converted stoichiometrically to dhydroartemisinin. Conventional doses of artesunate are safe and effective when given to patients with complications of falciparum malaria.
Publisher: Wiley
Date: 03-02-2004
Publisher: Wiley
Date: 02-1998
DOI: 10.1046/J.1365-2125.1998.00655.X
Abstract: To obtain comprehensive pharmacokinetic and pharmacodynamic data for artesunate (ARTS) and its active metabolite dihydroartemisinin (DHA) following i.v. and oral administration of ARTS to patients with acute, uncomplicated falciparum malaria. Twenty-six Vietnamese patients with falciparum malaria were randomized to receive either i.v. ARTS (120 mg group 1) or oral ARTS (100 mg group 2), with the alternative preparation given 8 h later in an open crossover design. Mefloquine (750 mg) was administered at 24 h. Plasma concentrations of ARTS and DHA were determined by h.p.l.c. assay. Pharmacokinetic parameters were calculated by non-compartmental methods. The time to 50% parasite clearance (PCT50) was calculated by linear interpolation of parasite density determinations. Linear least squares and multiple linear regression analyses were used to evaluate pharmacokinetic-pharmacodynamic relationships. Following i.v. bolus, ARTS had a peak concentration of 29.5 microM (11 mg l[-1]), elimination t1/2 = 2.7 min, CL = 2.33 l h(-1) kg(-1) and V = 0.14 l kg(-1). The Cmax for DHA was 9.3 microM (2.64 mg l[-1]), t1/2 = 40 min, CL =0.75 l h(-1) kg(-1) and V = 0.76 l kg(-1). Following oral ARTS, relative bioavailability of DHA was 82%, Cmax was 2.6 microM (0.74 mg l[-1]), t1/2 = 39 min, and MAT = 67 min. Overall, the PCT50 and fever clearance time (FCT) were 6.5 h and 24 h, respectively. There was no correlation between PCT50 or FCT and AUC, Cmax or MRT for DHA. Despite rapid clearance of ARTS and DHA in patients with uncomplicated falciparum malaria, prompt parasite and fever clearance were achieved. High relative bioavailability of DHA following oral ARTS administration, and clinical outcomes comparable with those after i.v. ARTS, support the use of the oral formulation in the primary care setting.
Publisher: Elsevier BV
Date: 04-2007
DOI: 10.1016/J.IJPARA.2006.10.011
Abstract: Reduced plasma retinol concentrations occur in human malaria but the benefits of supplementation remain uncertain. We assessed the in vivo efficacy of retinol administration, and its effect on lipid peroxidation, in a Plasmodium berghei murine model. Animals received vehicle (n=17) or retinol (i) before P. berghei inoculation (four doses), (ii) at parasitaemia 10-15% (three to four doses) or (iii) before and after inoculation (six to seven doses n=15 in each group), with euthanasia on day 8 post-inoculation or when the parasitaemia exceeded 50%. Multiple-dose pre-inoculation retinol reduced endpoint parasitaemia by 24% (P=0.001 versus controls). A reduction of 18% (P=0.042) was observed when retinol was given to parasitaemic animals. Retinol was ineffective when given both before and after infection (11% reduction P=0.47). Although retinol supplementation did not change plasma retinol concentrations, liver retinol content increased and correlated inversely with endpoint parasitaemia (r=-0.45, P=0.001). Malaria infection augmented concentrations of the free radical lipid peroxidation end-product F(2)-isoprostanes in plasma, erythrocytes and liver by 1.8-, 2.8- and 4.9-fold, respectively, but retinol supplementation had no effect on these increases. Consistent with some human malaria studies, prophylactic retinol reduces P. berghei parasitaemia. This effect relates to augmentation of tissue retinol stores rather than to retinol-associated changes in oxidant status.
Publisher: Elsevier BV
Date: 11-2017
DOI: 10.1016/J.JPBA.2017.08.030
Abstract: Advances in bioanalytical methods are facilitating micro-volume and dried blood spot (DBS) analysis of drugs in biological matrices for pharmacokinetic studies in children and neonates. We sought to develop a UPLC-MS/MS assay for simultaneous measurement of caffeine, pentoxifylline (PTX) and three metabolites of PTX in both plasma and DBS. Caffeine, PTX, the metabolites M1 (lisofylline), M4 and M5, and the internal standards (caffeine-d
Publisher: Wiley
Date: 03-09-2004
Publisher: Informa UK Limited
Date: 04-2014
Publisher: Wiley
Date: 08-1992
DOI: 10.1111/J.1445-5994.1992.TB02155.X
Abstract: Peptides HNB-92-169 and 116-169, tyr, derivatives of the C-terminal part of bovine myelin basic protein, sensitize rabbits for experimental allergic encephalomyelitis (EAE). Dissolving these peptides in heat-inactivated normal guinea-pig, human, or monkey serum immediately before emulsification with Freund's complete adjuvant (FCA) abrogated their disease-inducing activity. Dissolving them in homologous or autologous serum only slightly affected the encephalitogenicity.
Publisher: Informa UK Limited
Date: 25-12-2016
DOI: 10.1586/17512433.2016.1129273
Abstract: The use of pharmacokinetic (PK) and pharmacodynamic (PD) data to inform antimalarial treatment regimens has accelerated in the past few decades, due in no small part to the stimulus provided by progressive development of parasite resistance to most of the currently available drugs. An understanding of the disposition, interactions, efficacy and toxicity of the mainstay of contemporary antimalarial treatment, artemisinin combination therapy (ACT), has been facilitated by PK/PD studies which have been used to refine treatment regimens across the spectrum of disease, especially in special groups including young children and pregnant women. The present review highlights recent clinically-important ex les of the ways in which these quantitative pharmacology tools have been applied to improve ACT, as well as 8-aminoquinoline use and the characterisation of novel antimalarial therapies such as the spiroindolones.
Publisher: American Society for Microbiology
Date: 21-09-2020
DOI: 10.1128/AAC.00874-20
Abstract: Ceftriaxone is widely used for respiratory and urinary infections in elderly and frail patients, but there are few pharmacokinetic studies. A prospective population pharmacokinetic study of ceftriaxone in adults over 65 years old was undertaken. Dried blood spots collected at baseline (predose) and 0.5, 1, 4, 8, and 24 h after administration of 1 g of ceftriaxone were assayed using a validated liquid chromatography-mass spectroscopy analytical method. Frailty was classified using the Edmonton frailty scale and grip strength via a hand dynamometer.
Publisher: Wiley
Date: 27-03-2016
DOI: 10.1111/BCP.12910
Publisher: Springer Science and Business Media LLC
Date: 04-12-2018
DOI: 10.1007/S00228-018-2597-Z
Abstract: Ertapenem is used off-label to treat osteoarticular infections but there are few pharmacokinetic (PK) data to guide optimal dosing strategies in patients who may be obese with multiple co-morbidities including diabetes and peripheral vascular disease. Participants undergoing lower limb utation or elective joint arthroplasty received a dose of intravenous ertapenem prior to surgery. Eight plasma s les were collected over 24 h, together with at least one bone s le per patient. Ertapenem concentrations in plasma and bone were measured using liquid-chromatography/mass-spectroscopy and analysed using non-linear mixed effects PK modelling. Plasma and bone concentrations were obtained from 10 participants. The final population PK model showed that a fat free body mass was the most appropriate body size adjustment. Ertapenem diffused rapidly into bone but concentrations throughout the 24 h dosing period were on average 40-fold higher in plasma, corresponding to a bone to plasma ratio of 0.025, and highly variable between in iduals. Simulations demonstrated a high probability of target attainment (PTA) for free plasma concentrations when the minimum inhibitory concentrations (MIC) were ≤ 0.25 mg/L. By contrast, at MICs of 0.5 mg/L and ≥ 1 mg/L, the fractions of patients attaining this target was ~ 80% and 40%, respectively. In bone, the PTA was ≤ 45% when the MIC was ≥ 0.25 mg/L. Local bone and free plasma concentrations appear adequate for osteoarticular infections where Enterobacteriaceae are the main causative pathogens, but for Staphylococcus aureus and other bacteria, conventional dosing may lead to inadequate PTA.
Publisher: Elsevier BV
Date: 04-2008
DOI: 10.1016/J.EXPPARA.2007.10.011
Abstract: Clinical reports indicate that malaria-infected asplenic patients have a reduced capacity for parasite clearance despite intensive antimalarial therapy. The aim of this study was to evaluate the efficacy of dihydroartemisinin in an asplenic murine malaria model. Mice were inoculated with Plasmodium berghei parasitised erythrocytes and received a single dose of dihydroartemisinin 56 h later, at 2-5% parasitaemia. Haematology, liver biochemistry and histopathology of key organs were performed to evaluate organ response to malaria infection. The nadir parasitaemia occurred 20 h after dihydroartemisinin administration, falling 2.8- to 6.0-fold and 2.7- to 6.9-fold in asplenic and intact mice, respectively, (10-100 mg/kg). Histopathology indicated increased stimulation of liver function/activity during malaria infection of asplenic mice (as compared to intact mice). Overall efficacy of single-dose dihydroartemisinin treatment in asplenic mice was similar to intact mice although the rate of recrudescence in asplenic mice was significantly greater than intact mice at 30 and 100 mg/kg. The asplenic murine malaria model could be used in pre-clinical studies of splenic function and clearance of malaria parasites, pathophysiological studies or antimalarial drug efficacy in asplenia.
Publisher: American Society for Microbiology
Date: 08-2017
DOI: 10.1128/AAC.00252-17
Abstract: Rheumatic heart disease (RHD) remains an important global health challenge. Administration of benzathine penicillin (BPG) every 3 to 4 weeks is recommended as a secondary prophylaxis to prevent recurrent episodes of acute rheumatic fever and subsequent RHD. Following intramuscular injection, BPG is hydrolyzed to penicillin G (benzylpenicillin). However, little is known of the pharmacokinetics (PK) of BPG in pediatric populations at high risk of RHD or of the pharmacokinetic-pharmacodynamic relationship between penicillin exposure and clinically relevant outcomes. Dried blood spot (DBS) assays can facilitate PK studies in situations where frequent venous blood s ling is logistically difficult. A liquid chromatography-mass spectroscopy assay for penicillin G in plasma and DBS was developed and validated. Application of the DBS assay for PK studies was confirmed using s les from adult patients receiving penicillin as part of an infection management plan. The limit of quantification for penicillin G in DBS was 0.005 mg/liter. Penicillin G is stable in DBS for approximately 12 h at room temperature (22°C), 6 days at 4°C, and month at −20°C. Plasma and DBS penicillin G concentrations for patients receiving BPG and penicillin G given via bolus doses correlated well and had comparable time-concentration profiles. There was poor correlation for patients receiving penicillin via continuous infusions, perhaps as a result of the presence of residual penicillin in the peripherally inserted central catheter, from which the plasma s les were collected. The present DBS penicillin G assay can be used as a surrogate for plasma concentrations to provide valid PK data for studies of BPG and other penicillin preparations developed to prevent rheumatic fever and RHD.
Publisher: Public Library of Science (PLoS)
Date: 11-06-2021
DOI: 10.1371/JOURNAL.PNTD.0009399
Abstract: Intramuscular benzathine penicillin G (BPG) injections are a cornerstone of secondary prophylaxis to prevent acute rheumatic fever (ARF) and rheumatic heart disease (RHD). Uncertainties regarding inter-ethnic and preparation variability, and target exposure profiles of BPG injection are key knowledge gaps for RHD control. To evaluate BPG pharmacokinetics (PK) in patients receiving 4-weekly doses in Ethiopia, we conducted a prospective cohort study of ARF/RHD patients attending cardiology outpatient clinics. Serum s les were collected weekly for one month after injection and assayed with a liquid chromatography-mass spectroscopy assay. Concentration-time datasets for BPG were analyzed by nonlinear mixed effects modelling using NONMEM. A total of 190 penicillin concentration s les from 74 patients were included in the final PK model. The median age, weight, BMI was 21 years, 47 kg and 18 kg/m 2 , respectively. When compared with estimates derived from Indigenous Australian patients, the estimate for median (95% confidence interval) volume of distribution (V/F) was lower (54.8 [43.9–66.3] l.70kg -1 ) whilst the absorption half-life (t 1/2-abs2 ) was longer (12.0 [8.75–17.7] days). The median (IQR) percentage of time where the concentrations remained above 20 ng/mL and 10 ng/mL within the 28-day treatment cycle was 42.5% (27.5–60) and 73% (58.5–99), respectively. The majority of Ethiopian patients receiving BPG as secondary prophylaxis to prevent RHD do not attain target concentrations for more than two weeks during each 4-weekly injection cycle, highlighting the limitations of current BPG strategies. Between-population variation, together with PK differences between different preparations may be important considerations for ARF/RHD control programs.
Publisher: American Society for Microbiology
Date: 2008
DOI: 10.1128/AAC.00555-07
Abstract: The disposition of chloroquine (CQ) and the related 4-aminoquinoline, piperaquine (PQ), were compared in Papua New Guinean children with uncomplicated malaria. Twenty-two children were randomized to 3 days of PQ phosphate at 20 mg/kg/day (12 mg of PQ base/kg/day) coformulated with dihydroartemisinin (DHA-PQ), and twenty children were randomized to 3 days of CQ at 10 mg base/kg/day with a single dose of sulfadoxine-pyrimethamine (CQ-SP). After a 42-day intensive s ling protocol, PQ, CQ, and its active metabolite monodesethyl-chloroquine (DECQ) were assayed in plasma by using high-performance liquid chromatography. A two-compartment model with first-order absorption was fitted to the PQ and CQ data. There were no significant differences in age, gender, body weight, or admission parasitemia between the two groups. The PCR-corrected 42-day adequate clinical and parasitological responses were 100% for DHA-PQ and 94% for CQ-SP, but P. falciparum reinfections during follow-up were common (33 and 18%, respectively). For PQ, the median volume of distribution at steady state, allowing for bioavailability ( V ss /F), was 431 liters/kg (interquartile range [IQR], 283 to 588 liters/kg), the median clearance (CL/F) was 0.85 liters/h/kg (IQR, 0.67 to 1.06 liters/h/kg), the median distribution half-life ( t 1/2 α ) was 0.12 h (IQR, 0.05 to 0.66 h), and the median elimination half-life ( t 1/2 β ) was 413 h (IQR, 318 to 516 h). For CQ, the median V ss /F was 154 liters/kg (IQR, 101 to 210 liters/kg), the median CL/F was 0.80 liters/h/kg (IQR, 0.52 to 0.96 liters/h/kg), the median t 1/2 α was 0.43 h (IQR, 0.05 to 1.82 h), and the median t 1/2 β was 233 h (IQR, 206 to 298 h). The noncompartmentally derived median DECQ t 1/2 β was 290 h (IQR, 236 to 368 h). Combined molar concentrations of DECQ and CQ were higher than those of PQ during the elimination phase. Although PQ has a longer t 1/2 β than CQ, its prompt distribution and lack of active metabolite may limit its posttreatment malaria-suppressive properties.
Publisher: Oxford University Press (OUP)
Date: 06-2004
Abstract: The principal aim of this study was to assess the potential value of final-year undergraduate pharmacy students in domiciliary medication review (DMR). Students attended workshops on communication skills, complementary medicines and medication review. Each student contacted 5–10 patients by telephone and asked them to identify from memory all current medications. The student later conducted a DMR in the patient's home and prepared a report for the pharmacist preceptor and the patient's medical practitioner (GP) to review. The students recruited 189 patients, 80% of whom were over 60 years of age. The mean number of medications recalled by patients (5.8±2.9) was significantly lower than the number of medications that patients were actually taking (8.5 ± 3.5 P & .001). Overall, 39% of patients gave incorrect/unknown indications for at least one medication and 17% had expired medicines. Students identified an average of 2.1 ± 1.7 actual or potential medication problems per patient. The mean number of problems endorsed by the pharmacist and GP were 1.1 and 0.9, and an additional 0.4 and 0.2 problems were identified, respectively. Nineteen patients (10%) required changes in therapy. Pharmacists and GPs thought it was appropriate for students to conduct DMRs under supervision and to include DMR as part of the students' training. Final-year pharmacy students were capable of collecting and collating medication information for DMRs in the community setting. The programme was acceptable to patients, GPs and pharmacist preceptors. Experience in DMRs should be included in the education of pharmacy students and pre-registration trainees.
Publisher: American Society for Microbiology
Date: 2016
DOI: 10.1128/AAC.01740-15
Abstract: Dried blood spot (DBS) antibiotic assays can facilitate pharmacokinetic harmacodynamic (PK/PD) studies in situations where venous blood s ling is logistically and/or ethically problematic. In this study, we aimed to develop, validate, and apply a DBS ceftriaxone assay. A liquid chromatography-tandem mass spectroscopy (LC-MS/MS) DBS ceftriaxone assay was assessed for matrix effects, process efficiency, recovery, variability, and limits of quantification (LOQ) and detection (LOD). The effects of hematocrit, protein binding, red cell partitioning, and chad positioning were evaluated, and thermal stability was assessed. Plasma, DBS, and cell pellet ceftriaxone concentrations in 10 healthy adults were compared, and plasma concentration-time profiles of DBS and plasma ceftriaxone were incorporated into population PK models. The LOQ and LOD for ceftriaxone in DBS were 0.14 mg/liter and 0.05 mg/liter, respectively. Adjusting for hematocrit, red cell partitioning, and relative recovery, DBS-predicted plasma concentrations were comparable to measured plasma concentrations ( r 0.95, P 0.0001), and Bland-Altman plots showed no significant bias. The final population PK estimates of clearance, volume of distribution, and time above threshold MICs for measured and DBS-predicted plasma concentrations were similar. At 35°C, 21°C, 4°C, −20°C, and −80°C, ceftriaxone retained % initial concentrations in DBS for 14 h, 35 h, 30 days, 21 weeks, and months, respectively. The present DBS ceftriaxone assay is robust and can be used as a surrogate for plasma concentrations to provide valid PK and PK/PD data in a variety of clinical situations, including in studies of young children and of those in remote or resource-poor settings.
Publisher: Wiley
Date: 2002
DOI: 10.1046/J.0306-5251.2001.01519.X
Abstract: To obtain pharmacokinetic data for artesunate (ARTS) and its active metabolite dihydroartemisinin (DHA) following i.m. ARTS and rectal DHA administration. Twelve Vietnamese patients with uncomplicated falciparum malaria were randomized to receive either i.v. or i.m. ARTS (120 mg), with the alternative preparation given 8 h later in an open crossover design. A further 12 patients were given i.v. ARTS (120 mg) at 0 h and rectal DHA (160 mg) 8 h later. Following i.v. bolus, ARTS had a peak concentration of 42 microm (16 mg l(-1), elimination t1/2 = 3.2 min, CL = 2.8 l h(-1) kg(-1) and V = 0.22 l kg(-1) . The Cmax for DHA was 9.7 microm (2.7 mg l(-1) ), t1/2 = 59 min, CL = 0.64 l h(-1) kg(-1) and V = 0.8 l kg(-1) . Following i.m. ARTS, Cmax was 2.3 microm (3.7 mg l(-1)), the apparent t1/2 = 41 min, CL = 2.9 l h(-1) kg(-1) and V = 2.6 l kg(-1). The relative bioavailability of DHA was 88%, Cmax was 4.1 microm (1.16 mg l(-1)) and t1/2 = 64 min. In the rectal DHA study, relative bioavailability of DHA was 16%. For patients with uncomplicated falciparum malaria i.m. ARTS is a suitable alternative to i.v. ARTS, at equal doses. To achieve plasma DHA concentrations equivalent to parenteral administration of ARTS, rectal DHA should be given at approximately four-fold higher milligram doses. Further studies are needed to determine whether these recommendations can be applied to patients with severe malaria.
Publisher: Wiley
Date: 05-1990
DOI: 10.1111/J.1464-410X.1990.TB14790.X
Abstract: Doxorubicin (1 mg/ml) was shown to be stable when added to urine s les with a mean natural pH of 5.4 and in urine buffered to a mean pH of 4.6. However, at alkaline pH (mean = 8.1) there was a biphasic degradation of doxorubicin (mean t1/2 = 3.24 and 89 h respectively). The data indicate that buffering intravesical doxorubicin to pH 4.6 (acetate buffer) or pre-dosing of patients with ammonium chloride may minimise loss of active drug during the time for which the drug is retained in the bladder. Recovery of doxorubicin following 1 hour's retention in the bladder was similar (77%) for doses of 38/48 or 78 mg. It is suggested that a dose of 50 mg (1 mg/ml) is sufficient to ensure an adequate delivery of active drug to the bladder wall.
Publisher: American Society for Pharmacology & Experimental Therapeutics (ASPET)
Date: 09-2002
Abstract: The aim of this study was to elucidate the metabolic pathways for dihydroartemisinin (DHA), the active metabolite of the artemisinin derivative artesunate (ARTS). Urine was collected from 17 Vietnamese adults with falciparum malaria who had received 120 mg of ARTS i.v., and metabolites were analyzed by high-performance liquid chromatography-mass spectrometry (HPLC-MS). Human liver microsomes were incubated with [12-(3)H]DHA and cofactors for either glucuronidation or cytochrome P450-catalyzed oxidation. Human liver cytosol was incubated with cofactor for sulfation. Metabolites were detected by HPLC-MS and/or HPLC with radiochemical detection. Metabolism of DHA by recombinant human UDP-glucuronosyltransferases (UGTs) was studied. HPLC-MS analysis of urine identified alpha-DHA-beta-glucuronide (alpha-DHA-G) and a product characterized as the tetrahydrofuran isomer of alpha-DHA-G. DHA was present only in very small amounts. The ratio of the tetrahydrofuran isomer, alpha-DHA-G, was highly variable (median 0.75 range 0.09-64). Nevertheless, alpha-DHA-G was generally the major urinary product of DHA glucuronidation in patients. The tetrahydrofuran isomer appeared to be at least partly a product of nonenzymic reactions occurring in urine and was readily formed from alpha-DHA-G by iron-mediated isomerization. In human liver microsomal incubations, DHA-G (diastereomer unspecified) was the only metabolite found (V(max) 177 +/- 47 pmol min(-1) mg(-1), K(m) 90 +/- 16 microM). Alpha-DHA-G was formed in incubations of DHA with expressed UGT1A9 (K(m) 32 microM, V(max) 8.9 pmol min(-1) mg(-1)) or UGT2B7 (K(m) 438 microM, V(max) 10.9 pmol mg(-1) min(-1)) but not with UGT1A1 or UGT1A6. There was no significant metabolism of DHA by cytochrome-P450 oxidation or by cytosolic sulfotransferases. We conclude that alpha-DHA-G is an important metabolite of DHA in humans and that its formation is catalyzed by UGT1A9 and UGT2B7.
Publisher: Elsevier BV
Date: 04-2010
DOI: 10.1016/J.REPROTOX.2009.10.013
Abstract: Reproductive toxicity data for the antimalarial drug piperaquine (PQ) were obtained in pregnant mice (F(0)) and their offspring (F(1) and F(2)). PQ phosphate (0-300 mg/kg/day) was given to pregnant Swiss mice from gestational days 14-18. Two F(1) pups from each litter (one male and one female) proceeded to maturity and were mated within dose groups. Biochemical and haematological indices were determined, and liver and kidney histopathology was assessed in F(1) and F(2) mice at 4 weeks. There were no significant dose-related adverse effects, but leucocytes were mildly elevated (F(1) and F(2) mice) and serum albumin was reduced (F(1) only) in the 300 mg/kg/day group. Low plasma PQ concentrations were detected in F(1) mice at 4 and 8 weeks. Although we found no significant PQ toxicity, clinical data are lacking and monitoring of women and their infants for biochemical and haematological adverse effects is recommended when PQ is used in pregnancy.
Publisher: Elsevier BV
Date: 12-2021
DOI: 10.1016/J.XPHS.2021.08.035
Abstract: Pentoxifylline (PTX) is administered as 6- or 12-hour intravenous infusions in the treatment of sepsis or necrotizing enterocolitis in neonates however, there is a paucity of formal stability data for PTX in the end-use solution. We investigated PTX stability in the simulated clinical conditions of neonatal intensive care, where PTX injection is diluted to 5 mg/mL and administered via syringe pump. A stability-indicating high performance liquid chromatography (HPLC) assay was established for PTX. The clinical simulation stability study comprised PTX 5 mg/mL in 20 mL syringes and was conducted at three temperatures, all protected from light: refrigerator (4°C) room temperature (22°C) and incubator/humidicrib (35°C). PTX stability also was evaluated at room temperature and exposed to light. S les were drawn at pre-determined times over a 10 day period and stored frozen (-80°C) until assayed by HPLC. A single exponential equation was fitted to the concentration-time data to determine PTX stability. Forced degradation studies confirmed that PTX was stable at elevated temperature (up to 45°C), exposed to light and under acidic stress for up to 10 days, but subject to degradation under alkali and oxidative stress. PTX injection 5 mg/mL in 0.9% w/v sodium chloride or 5% w/v glucose was found to be stable when protected from light at 22°C and 35°C, and exposed to light at 22°C for at least 7 days. These data provide clinically relevant evidence that PTX injection is stable in the end-use, ICU/incubator clinical conditions for at least 24 hours.
Publisher: Wiley
Date: 11-09-2019
DOI: 10.1111/AJO.13046
Abstract: Postpartum haemorrhage (PPH) kits containing uterotonics are used on obstetric units for the timely management of PPH. Visible discolouration of ergometrine and ergometrine-oxytocin injections was observed in PPH kits stored in medical refrigerators on the obstetric unit at our hospital. To investigate the stability of ergometrine and ergometrine-oxytocin injections in PPH kits under simulated clinical storage conditions and to determine the potency of oules quarantined from PPH kits on our obstetric unit. Ergometrine and ergometrine-oxytocin injection oules were stored exposed to and protected from light at 4°C and room temperature (25°C) for up to three months, and assayed by high-performance liquid chromatography. Stability was based on the time for the ergometrine or oxytocin concentration to fall to 90% of the original concentration (t Ergometrine was stable at both temperatures for >6 months, when stored protected from light in simulated clinical conditions. When exposed to light, ergometrine was stable for approximately 4 days at 25°C and 10 days at 4°C. Discoloured ergometrine and ergometrine-oxytocin injection oules were found to be <90% of the nominal concentration. Stability of ergometrine in PPH kits is largely unaffected by temperature fluctuations (at 4°C and 25°C) over 6 months when protected from light. Ergometrine and ergometrine-oxytocin oules should be inspected prior to use and any discoloured oules discarded.
Publisher: American Society for Microbiology
Date: 07-2015
DOI: 10.1128/AAC.00326-15
Abstract: The tolerability, safety, and disposition of dihydroartemisinin (DHA) and piperaquine (PQ) were assessed in 32 pregnant (second/third trimester) and 33 nonpregnant Papua New Guinean women randomized to adult treatment courses of DHA-PQ (three daily doses) or sulfadoxine-pyrimethamine (SP)-PQ (three daily PQ doses, single dose of SP). All dose adminstrations were observed, and subjects fasted for 2 h postdose. Plasma PQ was assayed by using high-performance liquid chromatography, and DHA was assessed by using liquid chromatography-mass spectrometry. Compartmental pharmacokinetic models were developed using a population-based approach. Both regimens were well tolerated. There was an expected increase in the rate-corrected electrocardiographic QT interval which was independent of pregnancy and treatment. Two pregnant and two nonpregnant women had Plasmodium falciparum parasitemia which cleared within 48 h, and no other subject became slide positive for malaria during 42 days of follow-up. Of 30 pregnant women followed to delivery, 27 (90%) delivered healthy babies and 3 (10%) had stillbirths these obstetric outcomes are consistent with those in the general population. The area under the plasma PQ concentration-time curve (AUC 0–∞ ) was lower in the pregnant patients (median [interquartile range], 23,721 μg · h/liter [21,481 to 27,951 μg · h/liter] versus 35,644 μg · h/liter [29,546 to 39,541 μg · h/liter] P 0.001) in association with a greater clearance relative to bioavailability (73.5 liters/h [69.4 to 78.4] versus 53.8 liters/h [49.7 to 58.2] P 0.001), but pregnancy did not influence the pharmacokinetics of DHA. The apparent pharmacokinetic differences between the present study and results from other studies of women with uncomplicated malaria that showed no effect of pregnancy on the AUC 0–∞ of PQ and greater bioavailability may reflect differences in postdose fat intake, proportions of women with malaria, and/or racial differences in drug disposition.
Publisher: American Society for Microbiology
Date: 08-2016
DOI: 10.1128/AAC.00756-16
Abstract: Dried blood spot (DBS) antibiotic assays can facilitate pharmacokinetic (PK) harmacodynamic (PD) studies in situations where venous blood s ling is logistically difficult. We sought to develop, validate, and apply a DBS assay for rif in (RIF), fusidic acid (FUS), and ciprofloxacin (CIP). These antibiotics are considered active against organisms in biofilms and are therefore commonly used for the treatment of infections associated with prosthetic implants. A liquid chromatography-mass spectroscopy DBS assay was developed and validated, including red cell partitioning and thermal stability for each drug and the rif in metabolite desacetyl rif in (Des-RIF). Plasma and DBS concentrations in 10 healthy adults were compared, and the concentration-time profiles were incorporated into population PK models. The limits of quantification for RIF, Des-RIF, CIP, and FUS in DBS were 15 μg/liter, 14 μg/liter, 25 μg/liter, and 153 μg/liter, respectively. Adjusting for hematocrit, red cell partitioning, and relative recovery, DBS-predicted plasma concentrations were comparable to measured plasma concentrations for each antibiotic ( r 0.95 P 0.0001), and Bland-Altman plots showed no significant bias. The final population PK estimates of clearance, volume of distribution, and time above threshold MICs for measured and DBS-predicted plasma concentrations were comparable. These drugs were stable in DBSs for at least 10 days at room temperature and 1 month at 4°C. The present DBS antibiotic assays are robust and can be used as surrogates for plasma concentrations to provide valid PK and PK/PD data in a variety of clinical situations, including therapeutic drug monitoring or studies of implant infections.
Publisher: American Society for Microbiology
Date: 10-2018
DOI: 10.1128/AAC.00940-18
Abstract: Dried blood spot (DBS) antibiotic assays can facilitate pharmacokinetic (PK) studies in situations where venous blood s ling is logistically and/or ethically challenging. In this study, we aimed to demonstrate the validity of a DBS ceftriaxone assay in a PK study of children with severe illness from Papua New Guinea (PNG), a setting in which health care resources are limited and anemia is common.
Publisher: Springer Science and Business Media LLC
Date: 13-04-2016
DOI: 10.1007/S40265-016-0572-5
Abstract: Naphthoquine is a 4-aminoquinoline antimalarial drug first synthesised in China in 1986 but which was not developed for clinical use until the late 1990s. Early in vitro parasite sensitivity and in vivo efficacy data, together with a long terminal elimination half-life (up to 23 days), suggested that it could be used as monotherapy for uncomplicated falciparum and vivax malaria, but is now marketed as a single-dose, fixed co-formulation with artemisinin in a milligram per kilogram ratio of 1:2.5. This form of artemisinin combination therapy (ACT) has also shown high cure rates, especially in two randomised trials in which, consistent with World Health Organization recommendations for all ACTs, it was administered daily for 3 days rather than as single dose for Plasmodium falciparum and P. vivax infections (28-day adequate clinical and parasitological response ≥98.4 %). Although detailed safety monitoring has been performed in a minority of subjects, >4000 healthy volunteers and patients with malaria have been exposed to naphthoquine without any documented significant toxicity. As with other 4-aminoquinolines, naphthoquine is associated with prolongation of the electrocardiographic QT interval but not with cardiac or neurological events. It has been administered to children as young as 4 months of age but, due to a lack of pharmacokinetic, efficacy and toxicity data in young infants and in pregnant/lactating women, it should not be used in these vulnerable patient groups.With the emergence of parasite resistance to other ACTs, naphthoquine partnered with a potent artemisinin derivative may prove a viable alternative treatment for uncomplicated malaria.
Publisher: MDPI AG
Date: 03-12-2021
DOI: 10.3390/PHARMACEUTICS13122066
Abstract: Because of the need to replace the current clinical artemisinins in artemisinin combination therapies, we are evaluating fitness of amino-artemisinins for this purpose. These include the thiomorpholine derivative artemiside obtained in one scalable synthetic step from dihydroartemisinin (DHA) and the derived sulfone artemisone. We have recently shown that artemiside undergoes facile metabolism via the sulfoxide artemisox into artemisone and thence into the unsaturated metabolite M1 DHA is not a metabolite. Artemisox and M1 are now found to be approximately equipotent with artemiside and artemisone in vitro against asexual
Publisher: American Society for Microbiology
Date: 08-2006
DOI: 10.1128/AAC.00177-06
Abstract: In an in vitro assessment of antimalarial combinations, dihydroartemisinin (DHA) showed no interaction or was mildly antagonistic when combined with piperaquine, pyronaridine, or naphthoquine. Interactions between 4-aminoquinolines and related drugs were also indifferent/antagonistic. The clinical significance of mildly antagonistic DHA combinations is uncertain but may become important if parasite drug sensitivity declines.
Publisher: Elsevier BV
Date: 05-2023
Publisher: American Society for Microbiology
Date: 16-08-2022
DOI: 10.1128/AAC.00185-22
Abstract: Mass drug administration (MDA) with monthly dihydroartemisinin-piperaquine (DHA-PQP) appears useful in malaria control and elimination strategies. Determining the relationship between consecutive piperaquine phosphate (PQP) exposure and its impact on QT interval prolongation is a key safety consideration for MDA c aigns.
Publisher: BMJ
Date: 23-10-2023
Publisher: Wiley
Date: 09-1998
Publisher: Oxford University Press (OUP)
Date: 11-2004
Abstract: OBJECTIVE: To investigate the relationship between blood glucose-lowering therapy, glycaemia and ethnicity in urban Australians with type 2 diabetes. DESIGN: Prospective observational community-based study of diabetes care, control and complications. METHODS: We analysed cross-sectional data from 1057 patients, 238 from a southern European (SE) migrant background and 819 Anglo-Celts (AC). Follow-up data were available for 539 patients (113 SE, 426 AC) who had annual reviews over 4 years. RESULTS: The SE patients were of similar age to the AC patients but had longer diabetes duration, were less fluent in English and had less formal education. After adjustment for diabetes duration, glycosylated haemoglobin and glutamic acid decarboxylase antibody positivity in a logistic regression model, insulin use at study entry was approximately twice as frequent amongst SE as AC patients (odds ratio (95% confidence interval) 1.90 (1.20-3.02)). In the prospective arm, progression to insulin increased in both groups, from 18.0% at baseline to 22.1% at 4 years in SE and from 7.1% to 14.4% in AC patients. beta-cell function (%B) and insulin sensitivity (%S) using the homoeostasis model assessment in a subset of diet-treated patients at baseline showed that SE ethnicity was associated with lower %B and greater %S than in the AC group. CONCLUSIONS: SE patients with early non-antibody-mediated beta-cell failure progress to insulin requirement within the first 4-5 years of type 2 diabetes. This could reflect either a longer period of undiagnosed diabetes or a more rapid loss of beta-cell function after diagnosis.
Publisher: Wiley
Date: 22-10-2020
DOI: 10.1002/PRP2.668
Publisher: American Society for Microbiology
Date: 12-2007
DOI: 10.1128/AAC.00529-07
Abstract: Doxycycline is reported to impair second-generation parasite schizogony. The effects of doxycycline alone and combined with dihydroartemisinin were investigated in a murine malaria model. Doxycycline lowered the rate of parasite growth within 2 days, with maximum effect in 6 days. Addition of dihydroartemisinin led to an additive antimalarial effect.
Publisher: Elsevier BV
Date: 03-2004
Publisher: Elsevier BV
Date: 08-2012
DOI: 10.1016/J.JCHROMB.2012.06.019
Abstract: Sensitive bioanalytical methods are required for pharmacokinetic studies in children, due to the small volume and modest number of s les that can be obtained. We sought to develop a LC-MS assay for primaquine and its active metabolite, carboxyprimaquine, following simultaneous, solid phase extraction of both analytes from human plasma. The analysis was conducted on a single-quad LC-MS system (Shimadzu Model 2020) in ESI+ mode, with quantitation by selected ion monitoring. Primaquine, carboxyprimaquine and 8-aminoquinoline (internal standard) were separated using a mobile phase of 80:20 methanol:water with 0.1% (v/v) formic acid and a Luna C(18) HPLC column, at ambient temperature. Solid phase extraction of the analytes from plasma (0.5 mL) was achieved with Oasis(®) HLB cartridges. The retention times for primaquine, 8-aminoquinoline and carboxyprimaquine were 3.3, 5.7 and 8.5 min, respectively. The calibration curve range (2-1500 μg/L) was appropriate for the limits of quantification and detection for primaquine (2 μg/L and 1μ g/L, respectively) and carboxyprimaquine (2.5 μg/L and 1 μg/L) and the anticipated plasma concentrations of the analytes. Intra- and inter-day precision for both primaquine and carboxyprimaquine was <10% across the concentration range 5-1000 μg/L. Accuracy for both analytes was <15% (5-500 μg/L). This validated LC-MS method with solid phase extraction facilitates the simultaneous analysis of primaquine and carboxyprimaquine from small volumes of human plasma, with run time 85% and sensitivity of 1-2 μg/L.
Publisher: Elsevier BV
Date: 12-2007
DOI: 10.1016/J.IJPARA.2007.05.001
Abstract: Antimalarial treatment strategies based on in vitro studies are limited by the paucity of pharmacodynamic information for dosage regimen design. We postulated that a murine model could be used for pre-clinical stages of drug development, especially in dose-response studies and evaluation of combination therapies. Swiss mice infected with Plasmodium berghei parasites (2-5% starting parasitaemia) were given dihydroartemisinin (0-100 mg/kg single dose). Parasite density was regularly determined from thin blood films. A parasite population growth model comprising parasite multiplication, decline in erythrocyte count with increasing parasitaemia and parasite clearance after drug administration was developed. This model described the rise in parasitaemia following inoculation, the nadir following dihydroartemisinin administration, and the subsequent resurgence of parasitaemia (analogous to 'recrudescence'). At doses of 10, 30 and 100 mg/kg dihydroartemisinin, there was a graded response with 2.5+/-1, 5+/-1 and 12+/-4-fold decreases in parasitaemia, respectively. The nadir parasitaemia (at 21-27 h) was also dose-dependent. This study demonstrates that a murine malaria pharmacodynamic model is a valuable tool for understanding how single drugs and their dosing schedules alter the time course and level of infection.
Publisher: Oxford University Press (OUP)
Date: 15-04-2019
DOI: 10.1093/JAC/DKZ076
Publisher: American Society for Microbiology
Date: 05-2012
DOI: 10.1128/AAC.06250-11
Abstract: Artemisinin-naphthoquine (ART-NQ) is a coformulated antimalarial therapy marketed as a single-dose treatment in Papua New Guinea and other tropical countries. To build on limited knowledge of the pharmacokinetic properties of the components, especially the tetra-aminoquinoline NQ, we studied ART-NQ disposition in Papua New Guinea children aged 5 to 12 years with uncomplicated malaria, comparing a single dose (15 and 6 mg/kg of body weight) administered with water (group 1 n = 13), a single dose (22 and 9 mg/kg) with milk (group 2) ( n = 17), and two daily doses of 22 and 9 mg/kg with water (group 3 n = 16). The plasma NQ concentration was assayed by high-performance liquid chromatography, and the plasma ART concentration was assayed using liquid chromatography-mass spectrometry. Population-based multicompartment pharmacokinetic models for NQ and ART were developed. NQ disposition was best characterized by a three-compartment model with a mean absorption half-life ( t 1/2 ) of 1.0 h and predicted median maximum plasma concentrations that ranged as high as 57 μg/liter after the second dose in group 3. The mean NQ elimination t 1/2 was 22.8 days clearance relative to bioavailability (CL/ F ) was 1.1 liters/h/kg and volume at steady state relative to bioavailability ( V ss / F ) was 710 liters/kg. Administration of NQ with fat (8.5 g 615 kJ) versus water was associated with 25% increased bioavailability. ART disposition was best characterized by a two-compartment model with a mean CL/ F (4.1 liters/h/kg) and V / F (21 liters/kg) similar to those of previous studies. There was a 77% reduction in the bioavailability of the second ART dose (group 3). NQ has pharmacokinetic properties that confirm its potential as an artemisinin partner drug for treatment of uncomplicated pediatric malaria.
Publisher: Elsevier BV
Date: 08-2022
Publisher: American Society for Microbiology
Date: 07-2015
DOI: 10.1128/AAC.00327-15
Abstract: Transfer of piperaquine (PQ) into breast milk was examined in 27 Papua New Guinean women given a 3-day course of dihydroartemisinin-PQ or sulfadoxine-pyrimethamine-PQ during the second/third trimester. Breast milk was s led on days 1, 2, 3 to 5, 7 to 11, and 14 to 17 postdelivery, a median of 70 days postdose (range, 6 to 145 days). A blood s le was taken at delivery, and additional serial s les were available from 9 women who delivered within 42 days of dosing. Milk and plasma PQ were assayed by high-performance liquid chromatography. A population-based approach was used to model the log e (plasma) and milk concentration-time data. A sigmoid E max model best described PQ breast milk transfer. The population average milk:plasma PQ ratio was 0.58, with a peak of 2.5 at delivery. The model-derived maximum milk intake (148 ml/kg of body weight/day) was similar to the accepted value of 150 ml/kg/day. The median estimated absolute and relative cumulative infant PQ doses were 22 μg and 0.07%, respectively, corresponding to absolute and relative daily doses of 0.41 μg/kg and 0.004%. Model-based simulations for PQ treatment regimens given at birth, 1 week postdelivery, and 6 weeks postdelivery showed that the highest median estimated relative total infant dose (0.36% median absolute total dose of 101 μg/kg) was seen after maternal PQ treatment 6 weeks postpartum. The maximum simulated relative total and daily doses from any scenario were 4.3% and 2.5%, respectively, which were lower than the recommended 10% upper limit. Piperaquine is transferred into breast milk after maternal treatment doses, but PQ exposure for suckling infants appears safe.
Publisher: Springer Science and Business Media LLC
Date: 26-06-2014
Publisher: Springer Science and Business Media LLC
Date: 05-2011
DOI: 10.1007/S12272-011-0509-1
Abstract: Dihydroartemisinin (DHA) is a poorly water-soluble drug that displays low bioavailability after oral administration. Attempts have been made to improve the solubility of DHA. Yet, no information is available concerning improved bioavailability. This study aimed to improve the water solubility of DHA by two systems: solid dispersions with polyvinylpyrrolidone (PVPK30, PVPK25, PVPK15) and inclusion complexes with hydroxypropyl-β-cyclodextrin (HPβCD), as well as improving the bioavailability of both systems. The phase transition of DHA with hydrophilic polymers was evaluated by X-ray diffraction (XRD) and differential scanning calorimetery (DSC). DHA became amorphous in DHA-HPβCD complexes and showed more amorphous behavior in XRD analyses with rise in molecular weight of PVP. Melting onset temperature of DHA decreased, while DSC thermograms revealed the peak area and enhanced enthalpy change (DH) in solid dispersions as well as inclusion complexes. DHA solubility was enhanced 84-fold in DHA-HPβCD complexes and 50-times in DHA-PVPK30. The improved solubility using the four polymers was in the following order: HPβCD > PVPK30 > PVPK25 > PVPK15. Values of area under curve (AUC) and half life (t(1/2)) of DHA-PVPK30 were highest followed by DHA-HPβCD, DHA-PVPK15 and DHA-PVPK25. V(d)/f of DHA-PVPK30 was 7-fold. DHA-HPβCD, DHA-PVPK15 and DHA-PVPK25 showed significantly different pharmacokinetic parameters compared with DHA solutions. The 95% confidence interval was meaningful in AUC and t(1/2). Pharmacokinetic parameters revealed that all four-test preparations were significantly more bioavailable than DHA alone.
Publisher: Elsevier BV
Date: 08-2003
DOI: 10.1016/S0001-706X(03)00118-9
Abstract: The study was a comparison of bioassay and HPLC analysis of artesunate (ARTS) and dihydroartemisinin (DHA) in plasma. ARTS and DHA in plasma s les from patients treated with ARTS were quantified by HPLC and expressed as DHA. DHA-equivalents in the same plasma s les were measured using a standardised parasite culture technique. DHA concentrations estimated by both methods were highly correlated (bioassay=0.96 x HPLC+11.0 r2=0.92). At high concentrations (>12000 nmol/l) bioassay sometimes overestimated DHA. Bioassay of active drug in plasma correlates well with specific chemical analysis by HPLC. ARTS and DHA appear to account for the total antimalarial activity in plasma after ARTS administration.
Publisher: American Society for Microbiology
Date: 10-2006
DOI: 10.1128/AAC.00708-06
Abstract: Bidirectional transport of four novel antimalarial compounds was determined using Caco-2 cell monolayers. P glycoprotein-mediated efflux was greatest for pyronaridine (5 to 20 μM) and low for naphthoquine (5 μM). With 20 μM naphthoquine, net efflux was blocked, suggesting saturation of the transporter. Piperaquine and dihydroartemisinin were not transported by the system.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-2003
Publisher: BMJ
Date: 24-11-2018
DOI: 10.1136/ARCHDISCHILD-2018-315376
Abstract: To investigate the physical and chemical compatibility of pentoxifylline (PTX) with a wide range of parenteral medications used in the neonatal intensive care setting. PTX and drug solutions were combined in glass phials and inspected visually for physical incompatibility. The chemical compatibility was evaluated on the basis of PTX concentrations. Precipitation, colour change or turbidity was not visible in any of the test mixtures, indicating no observed physical incompatibility or apparent risk of blockage in narrow-bore intravenous tubing. The PTX concentration was approximately 2.5% and 4.5% lower when combined with dopamine and amoxicillin, respectively. The PTX concentration ratios for all other combinations were in the range of 99%–102%. In simulated Y-site conditions, physical compatibility testing of PTX and 30 parenteral medications revealed no evidence of precipitation. Based on PTX concentration tests, it could be prudent to avoid mixing PTX with dopamine or amoxicillin.
Publisher: BMJ
Date: 23-12-2019
DOI: 10.1136/ARCHDISCHILD-2019-317912
Abstract: To investigate the physical and chemical compatibility of pentoxifylline (PTX) with a range of parenteral medications used in neonatal intensive care. PTX and drug solutions were combined in glass vials, inspected for physical incompatibility and evaluated on the basis of PTX concentrations for chemical compatibility. No precipitation, colour change or turbidity was observed in any of the test mixtures. The PTX concentration was approximately 5.5% lower when combined with undiluted calcium gluconate injection (100 mg/mL). The PTX concentration ratios for all other combinations, including diluted calcium gluconate injection (50 mg/mL), were in the range of 99.5%–102%. In simulated Y-site conditions, PTX was found to be compatible with 15 parenteral medications and six total parenteral nutrition solutions. Based on PTX concentration tests, it would be prudent to avoid mixing PTX with undiluted calcium gluconate injection.
Publisher: Oxford University Press (OUP)
Date: 09-2004
Abstract: To determine the status of adverse drug reaction (ADR) reporting in Australian hospitals. Method Postal questionnaire to all 299 directors of pharmacy in Australian hospitals. The response rate was 49.5%. Hospitals of different size were well represented: & beds (23%), 100–199 beds (35%) and 200–499 beds (30%). ADR policies were reported by 67% of pharmacy departments. In most hospitals, doctors or pharmacists were responsible for ADR submissions to the Australian ADR Advisory Committee (ADRAC). Follow-up action included reports to Drug and Therapeutics Committees (57%) and drug bulletins (37%). Advice on ADRs was forwarded to the patient, the general practitioner (GP) and the community pharmacist by 96%, 89% and 11% of hospitals. Methods of informing patients were verbal (91%), card (17%) or letter (13%). Methods used to notify GPs included discharge summary (70%), letter (26%) or via the patient (15%). Data from ADRAC indicated a median 2.5 (range 0–362) reports from participating hospitals in 2000. The median ADR reporting rate was 0.02% (range 0–1.09) of patient admissions. There was no association between ADR reporting rates and the existence of an ADR policy or a centralised ADR reporting system. There was an association between hospital ADR reporting rates and provision of feedback or a reward for ADR reporting (P& .001). Procedures or policies for ADR reporting are available in most Australian hospitals but this has no direct effect on ADR reporting rates. These findings suggest a gap between policy and implementation of ADR reporting. Strategies to improve ADR reporting could include improved feedback and electronic submissions to ADRAC from a centralised service.
Publisher: Elsevier BV
Date: 07-2008
DOI: 10.1016/J.TOX.2008.04.004
Abstract: Pharmacokinetic and toxicological data for piperaquine (PQ) - a bisquinoline antimalarial drug - are limited, despite strong evidence of clinical efficacy. Our aim was to conduct a detailed toxicological investigation of PQ in Swiss mice. The study comprised three phases: (i) oral PQ phosphate (PQP) at doses ranging from 0 to 600 mg/(kg day) for 5 days. Pathology tests included haematological and biochemical indices, and histopathology of the liver, heart and kidneys. (ii) PQP doses of 0-300 mg/(kg day) for 12 days and pathology tests as described. (iii) Pharmacokinetic parameters determined from mice given 100mg/(kg day) PQP for 5 days. Blood was harvested from mice over 56 days and plasma analysed by HPLC. Mice given low doses of PQ had stable, normal body and organ weights. Weight loss was observed in mice given high doses and was accompanied by increased liver and kidney weights. Principal haematological effects were modest fluctuations in total white cells and neutrophils biochemical effects were elevated ALT and low albumin in high-dose groups. Liver histopathology revealed minor cytoplasmic and inflammatory effects. PQ treatment did not affect heart muscle but minor renal changes were observed at high doses. Pharmacokinetic parameters were consistent with previous studies: t1/2, CL and V were 16 days, 1.36 L/(h kg) and 756 L/kg, respectively. PQ may cause minor hepatotoxicity and renal tubular cell damage, and adversely affect selected haematological indices, as demonstrated at cumulative doses approximately 50 times those recommended in humans. Significant effects in humans will likely be infrequent and dose-related.
Publisher: American Society for Microbiology
Date: 2008
DOI: 10.1128/AAC.00878-07
Abstract: Piperaquine (PQ) is an important partner in antimalarial treatment strategies. However, there is a paucity of detailed preclinical and pharmacokinetic data to link PQ serum concentrations and toxicity or efficacy. The aim of this study was to investigate the pharmacokinetics and pharmacodynamics of PQ in a murine malaria treatment model. The study comprised three arms. (i) PQ pharmacokinetic parameters were determined in healthy and malaria-infected mice (90 mg/kg PQ phosphate [PQP]). (ii) For determination of single-dose pharmacodynamics, Swiss mice were inoculated with Plasmodium berghei parasites and given PQP (10, 30, or 90 mg/kg intraperitoneally) at 2 to 5% starting parasitemia. After 60 days, the 90-mg/kg PQP group was reinoculated with P. berghei . (iii) Combination efficacy was investigated at doses of 10 mg/kg PQP and 30 mg/kg dihydroartemisinin (DHA). The median survival times were 4, 10, and 54 days for 0, 10, and 30 mg/kg PQP, respectively. All mice given 90 mg/kg PQP survived beyond 60 days, with a mean parasitemia of % before and after reinoculation. The nadir for DHA plus PQP was significantly lower (22-fold ± 12-fold) than the initial parasitemia for the in idual drugs (DHA, 12-fold ± 5-fold PQP, 13-fold ± 3-fold P = 0.007 [analysis of variance]). The elimination half-lives of PQ in healthy and infected mice were 18 and 16 days, respectively, and the extrapolated residual PQ concentration at 60 days ( μg/liter) was ineffective at suppressing P. berghei infection. PQ has a potent antimalarial effect after single-dose treatment, and its efficacy was enhanced by combination with DHA.
Publisher: American Society for Microbiology
Date: 10-2014
DOI: 10.1128/AAC.02538-14
Abstract: Pharmacopeial recommendations for administration of antimalarial drugs are the same weight-based (mg/kg of body weight) doses for children and adults. However, linear calculations are known to underestimate pediatric doses therefore, interspecies allometric scaling data may have a role in predicting doses in children. We investigated the allometric scaling relationships of antimalarial drugs using data from pharmacokinetic studies in mammalian species. Simple allometry ( Y = a × W b ) was utilized and compared to maximum life span potential (MLP) correction. All drugs showed a strong correlation with clearance (CL) in healthy controls. Insufficient data from malaria-infected species other than humans were available for allometric scaling. The allometric exponents ( b ) for CL of artesunate, dihydroartemisinin (from intravenous artesunate), artemether, artemisinin, clindamycin, piperaquine, mefloquine, and quinine were 0.71, 0.85, 0.66, 0.83, 0.62, 0.96, 0.52, and 0.40, respectively. Clearance was significantly lower in malaria infection than in healthy (adult) humans for quinine (0.07 versus 0.17 liter/h/kg P = 0.0002) and dihydroartemisinin (0.81 versus 1.11 liters/h/kg P = 0.04 power = 0.6). Interpolation of simple allometry provided better estimates of CL for children than MLP correction, which generally underestimated CL values. Pediatric dose calculations based on simple allometric exponents were 10 to 70% higher than pharmacopeial (mg/kg) recommendations. Interpolation of interspecies allometric scaling could provide better estimates than linear scaling of adult to pediatric doses of antimalarial drugs however, the use of a fixed exponent for CL was not supported in the present study. The variability in allometric exponents for antimalarial drugs also has implications for scaling of fixed-dose combinations.
Publisher: American Society for Microbiology
Date: 2013
DOI: 10.1128/AAC.01463-12
Abstract: Murine models are used to study erythrocytic stages of malaria infection, because parasite morphology and development are comparable to those in human malaria infections. Mechanism-based pharmacokinetic-pharmacodynamic (PK-PD) models for antimalarials are scarce, despite their potential to optimize antimalarial combination therapy. The aim of this study was to develop a mechanism-based growth model (MBGM) for Plasmodium berghei and then characterize the parasiticidal effect of dihydroartemisinin (DHA) in murine malaria (MBGM-PK-PD). Stage-specific (ring, early trophozoite, late trophozoite, and schizont) parasite density data from Swiss mice inoculated with Plasmodium berghei were used for model development in S-ADAPT. A single dose of intraperitoneal DHA (10 to 100 mg/kg) or vehicle was administered 56 h postinoculation. The MBGM explicitly reflected all four erythrocytic stages of the 24-hour P. berghei life cycle. Merozoite invasion of erythrocytes was described by a first-order process that declined with increasing parasitemia. An efflux pathway with subsequent return was additionally required to describe the schizont data, thus representing parasite sequestration or trapping in the microvasculature, with a return to circulation. A 1-compartment model with zero-order absorption described the PK of DHA, with an estimated clearance and distribution volume of 1.95 liters h −1 and 0.851 liter, respectively. Parasite killing was described by a turnover model, with DHA inhibiting the production of physiological intermediates (IC 50 , 1.46 ng/ml). Overall, the MBGM-PK-PD described the rise in parasitemia, the nadir following DHA dosing, and subsequent parasite resurgence. This novel model is a promising tool for studying malaria infections, identifying the stage specificity of antimalarials, and providing insight into antimalarial treatment strategies.
Publisher: Wiley
Date: 25-02-2013
DOI: 10.1111/NEP.12035
Abstract: Treatment of chronic kidney disease (CKD) includes parenteral iron therapy, and these infusions can lead to iron overload. Secondary iron overload is typically treated with iron chelators, of which deferasirox is one of the most promising. However, it has not been studied in patients with CKD and iron overload. A pilot study was conducted to evaluate the pharmacokinetics and safety of deferasirox in eight haemodialysis-dependent patients, who were receiving intravenous iron for treatment of anaemia of CKD. Deferasirox was administered at two doses (10 mg/kg and 15 mg/kg), either acute (once daily for 2 days) or steady-state (once daily for 2 weeks). A dose of 10 mg/kg in either protocol was not sufficient to achieve a plasma concentration in the therapeutic range (acute peak 14.1 and steady-state 22.8 μmol/L), while 15 mg/kg in either protocol maintained plasma concentration well above this range (acute peak 216 and steady-state 171 μmol/L). Plasma concentration observed at 15 mg/kg was well above that expected for this dose (40-50 μmol/L), although no adverse clinical events were observed. This study highlights the need to profile drugs such as deferasirox in specific patient groups, such as those with CKD and iron overload.
Publisher: Oxford University Press (OUP)
Date: 22-07-2020
DOI: 10.1093/JAC/DKAA282
Abstract: Benzathine penicillin G has been used as monthly deep intramuscular (IM) injections since the 1950s for secondary prevention of acute rheumatic fever and rheumatic heart disease (RHD). Injection frequency and pain are major programmatic barriers for adherence, prompting calls for development of better long-acting penicillin preparations to prevent RHD. We hypothesized that subcutaneous (SC) administration of benzathine penicillin G could delay penicillin absorption when compared with IM injections. To compare the pharmacokinetic profile and tolerability of benzathine penicillin G according to different routes of administration, 15 healthy males participated in a randomized crossover study to receive benzathine penicillin G by either SC or IM routes, with a 10 week washout period before the second dose by the alternative route. Ultrasound guidance confirmed injection location. Penicillin concentrations and pain scores were measured for 6 weeks following injections. SC administration was well tolerated with no significant differences in pain scores. Following SC injection, the principal absorption half-life (95% CI) was 20.1 (16.3–29.5) days and 89.6% (87.1%–92.0%) of the drug was directed via this pathway compared with 10.2 (8.6–12.5) days and 71.3% (64.9%–77.4%) following IM administration. Lower peak and higher trough penicillin concentrations resulted following SC injection. Simulations demonstrated that SC infusion of higher doses of benzathine penicillin G could provide therapeutic penicillin concentrations for 3 months. SC administration of benzathine penicillin G is safe and significantly delays penicillin absorption. High-dose benzathine penicillin G via the SC route would fulfil many product characteristics required for the next generation of longer-acting penicillins for use in RHD.
Publisher: Elsevier BV
Date: 09-2022
DOI: 10.1016/J.JIAC.2022.04.016
Abstract: The objectives of this study were to develop a stability-indicating high performance liquid chromatography (HPLC) assay for benzylpenicillin (BPC) in pharmaceutical fluids, and to investigate the stability of (i) isotonic citrate-buffered BPC solutions at the clinically relevant concentration of 30 mg/mL, and (ii) low concentration citrate-buffered BPC intravenous infusions (5-30 μg/mL). The stability of isotonic BPC solutions containing 3.4 or 7.2 mg/mL sodium citrate was compared against contemporary hypertonic solutions. The HPLC assay was shown to be stability-indicating following acidic, alkali, oxidative and elevated temperature stress testing. After 7 d storage at 4 °C and 24 h at 35 °C, the concentrations of isotonic BPC 30 mg/mL solutions containing 3.4 and 7.2 mg/mL sodium citrate were 96% and 95% respectively, compared to day 0. After 3 d at 4 °C and 24 h at room temperature (22 °C), the concentrations of isotonic BPC solutions with 3.4 and 7.2 mg/mL sodium citrate were 99% and 96% respectively, compared to day 0. These data were comparable to the hypertonic solutions and meet pharmacopeial stability requirements. Low concentration BPC infusions showed 0.5% and 2.5% degradation after 24 h storage at 22 °C and 35 °C, respectively. The isotonic BPC 30 mg/mL formulation is simple to prepare and may offer clinical benefits in settings where hypertonic solutions are problematic. This study provides assurance that high- and low-dose isotonic BPC infusions are stable at room temperature and our findings may be applicable to in vitro studies of BPC.
Publisher: American Society for Microbiology
Date: 07-2009
DOI: 10.1128/AAC.00056-09
Abstract: Piperaquine (PQ) is an important partner drug in antimalarial combination treatments, but the long half-life of PQ raises concerns about drug resistance. Our aim was to investigate the extended antimalarial effect of PQ in a study of drug efficacy, reinoculation outcomes, and parasite viability after the administration of a single dose of PQ in the murine malaria model. Initially, male Swiss mice were inoculated with Plasmodium berghei and at 64 h after parasite inoculation were given PQ phosphate at 90 mg/kg of body weight intraperitoneally. Parasite viability, drug efficacy, reinoculation responses, and parasite resistance were determined at 25, 40, 60, 90, and 130 days after drug administration. At each time point, six mice were reinoculated with 10 7 P. berghei parasites and blood was harvested from another four mice for viability passage into naïve mice ( n = 5 for each blood s le) and from another two mice for determination of the plasma PQ concentration. The efficacy study demonstrated that the residual PQ concentrations did not suppress the infection after 25 days. Viable parasites were present up to 90 days after PQ dosing, although only 50% and 25% of the passaged parasites remained viable at 60 and 90 days postdosing, respectively. Viable parasites passaged into the naïve hosts were generally resistant to PQ when they were exposed to the drug for a second time. PQ was found to have a substantial antimalarial effect in this model, and the effect appears to be sufficient for a host immunological response to be established, resulting in the long-term survival of P. berghei -infected mice.
Publisher: Elsevier BV
Date: 12-2011
DOI: 10.1016/J.BMC.2011.10.037
Abstract: A series of mono- and di-substituted analogues of isocryptolepine have been synthesized and evaluated for in vitro antimalarial activity against chloroquine sensitive (3D7) and resistant (W2mef) Plasmodium falciparum and for cytotoxicity (3T3 cells). Di-halogenated compounds were the most potent derivatives and 8-bromo-2-chloroisocryptolepine displayed the highest selectivity index (106 the ratio of cytotoxicity (IC(50)=9005 nM) to antimalarial activity (IC(50)=85 nM)). Our evaluation of novel isocryptolepine compounds has demonstrated that di-halogenated derivatives are promising antimalarial lead compounds.
Publisher: American Society for Microbiology
Date: 08-2011
DOI: 10.1128/AAC.00067-11
Abstract: Chloroquine (CQ) is an important antimalarial drug for the treatment of special patient groups and as a comparator for preclinical testing of new drugs. Pharmacokinetic data for CQ in animal models are limited thus, we conducted a three-part investigation, comprising (i) pharmacodynamic studies of CQ and CQ plus dihydroartemisinin (DHA) in Plasmodium berghei -infected mice, (ii) pharmacokinetic studies of CQ in healthy and malaria-infected mice, and (iii) interspecies allometric scaling for CQ from 6 animal and 12 human studies. The single-dose pharmacodynamic study (10 to 50 mg CQ/kg of body weight) showed dose-related reduction in parasitemia (5- to -fold) and a nadir 2 days after the dose. Multiple-dose regimens (total dose, 50 mg/kg CQ) demonstrated a lower nadir and longer survival time than did the same single dose. The CQ-DHA combination provided an additive effect compared to each drug alone. The elimination half-life ( t 1/2 ), clearance (CL), and volume of distribution ( V ) of CQ were 46.6 h, 9.9 liters/h/kg, and 667 liters/kg, respectively, in healthy mice and 99.3 h, 7.9 liters/h/kg, and 1,122 liters/kg, respectively, in malaria-infected mice. The allometric equations for CQ in healthy mammals (CL = 3.86 × W 0.56 , V = 230 × W 0.94 , and t 1/2 = 123 × W 0.2 ) were similar to those for malaria-infected groups. CQ showed a delayed dose-response relationship in the murine malaria model and additive efficacy when combined with DHA. The biphasic pharmacokinetic profiles of CQ are similar across mammalian species, and scaling of specific parameters is plausible for preclinical investigations.
Publisher: Public Library of Science (PLoS)
Date: 23-03-2015
Publisher: Wiley
Date: 19-12-2014
DOI: 10.1111/BCP.12288
Publisher: Wiley
Date: 08-2023
DOI: 10.1002/PED4.12393
Publisher: SAGE Publications
Date: 11-2005
DOI: 10.1177/14746514050050061001
Abstract: Pharmaceutical care (PC) is a process through which a pharmacist works with other healthcare professionals and the patient to optimise pharmacotherapy. Early studies, carried out before PC was established, provided limited evidence of the benefits of pharmacist involvement in diabetes management. More recent research has examined the role of PC in a range of diabetic sub-groups. Although few of these studies were randomised, prospective and included clinically important end points such as HbA1C, some beneficial effects of PC were reported. In the most recent study, a 12-month randomised controlled trial of PC in community-based diabetic patients, regular face-to-face and telephone interviews with an experienced clinical pharmacist improved glycosylated haemoglobin while glycaemic control did not change in the controls. In addition, reductions in blood pressure, and in absolute vascular risk for patients with no history of coronary artery disease, were significantly greater in the PC group. Available evidence suggests that PC can prove a valuable component of community-based multi-disciplinary diabetes care.
Publisher: American Society for Microbiology
Date: 2003
DOI: 10.1128/AAC.47.1.368-370.2003
Abstract: Penetration of cerebrospinal fluid (CSF) by artesunate and DHA was assessed in six adults with cerebral or severe malaria. Lumbar punctures were performed on admission and during convalescence, at 15 min (patient 1), 30 min (patient 2), 45 min (patient 3), 60 min (patient 4), 90 min (patient 5), and 120 min (patient 6) after intravenous administration of 120 mg of artesunate. No artesunate was detectable in CSF. In both studies, DHA levels in CSF increased with time while dihydroartemisinin levels in plasma fell. Dihydroartemisinin might accumulate in CSF during frequent artesunate dosing.
Publisher: Elsevier BV
Date: 09-2023
Publisher: American Diabetes Association
Date: 04-2005
Abstract: OBJECTIVE—To examine the effect of a 12-month pharmaceutical care (PC) program on vascular risk in type 2 diabetes. RESEARCH DESIGN AND METHODS—We recruited 198 community-based patients randomized to PC or usual care. PC patients had face-to-face goal-directed medication and lifestyle counseling at baseline and at 6 and 12 months plus 6-weekly telephone assessments and provision of other educational material. Clinical, biochemical, and medication-related data were sent regularly to each patient’s physician(s). The main outcome measure was change in HbA1c. A diabetes-specific risk engine was used to estimate changes in 10-year coronary heart disease (CHD) and stroke risk in patients without a history of cardiovascular disease. RESULTS—At total of 180 patients (91%) completed the study. Mean (95% CI) reductions were greater in PC case subjects (n = 92) than control subjects (n = 88) for HbA1c (−0.5% [95% CI −0.7 to −0.3] vs. 0 [−0.2 to 0.2]) and systolic (−14 mmHg [−19 to −9] vs. −7 [−11 to −2]) and diastolic (−5 mmHg [−8 to −3] vs. −2 [−4 to 1]) blood pressure (P ≤ 0.043). The improvement in HbA1c persisted after adjustment for baseline value and demographic and treatment-specific variables. The median (interquartile range) 10-year estimated risk of a first CHD event decreased in the PC case subjects (25.1% [15.6–36.2] to 20.3 [14.6–30.2] n = 42, P = 0.002) but not in the control subjects (26.1% [17.2–39.4] vs. 26.4 [16.7–38.0] n = 52, P = 0.17). CONCLUSIONS—A 12-month PC program in type 2 diabetes reduced glycemia and blood pressure. Pharmacist involvement contributed to improvement in HbA1c independently of pharmacotherapeutic changes. PC could prove a valuable component of community-based multidisciplinary diabetes care.
Publisher: Oxford University Press (OUP)
Date: 28-04-2014
DOI: 10.1093/JAC/DKU120
Abstract: To develop a mechanism-based model that describes the time course of the malaria parasite in infected mice receiving a combination therapy regimen of dihydroartemisinin and piperaquine. Total parasite density-time data from Swiss mice inoculated with Plasmodium berghei were used for the development of population models in S-ADAPT. The mice were administered a single intraperitoneal dose of 30 mg/kg dihydroartemisinin, 10 mg/kg piperaquine phosphate or a combination of both antimalarials at 64 h post-inoculation. In a separate study, mice received multiple dihydroartemisinin doses (5 × 10 mg/kg or 30 mg/kg dihydroartemisinin followed by two 10 mg/kg doses). Parasite recrudescence after treatment was defined using a model that incorporated each erythrocytic stage of the P. berghei life cycle. The disposition of dihydroartemisinin and piperaquine was described by a one-compartment and two-compartment model, respectively. The estimated clearance was 1.95 L/h for dihydroartemisinin and 0.109 L/h for piperaquine. A turnover model described the parasite killing curve after single-agent dosing, with an estimated mean IC50 of 0.747 μg/L for dihydroartemisinin and 16.8 μg/L for piperaquine. In addition, the rate of parasite killing by dihydroartemisinin was almost 50-fold faster than for piperaquine. Parameters from the monotherapy models adequately described the parasite density-time curve following dihydroartemisinin iperaquine combination therapy or multiple-dose regimens of dihydroartemisinin. This study has developed mechanistic models that describe the parasite-time curve after single, multiple or combination dosing of antimalarials to mice. These structural models have potential application for pre-clinical investigations to design and refine artemisinin-based combination therapy dosage regimens.
Publisher: Elsevier BV
Date: 03-1996
DOI: 10.1016/0378-4347(95)00428-9
Abstract: A novel solid-phase extraction and a robust high-performance liquid chromatographic (HPLC) separation procedure for artesunate and alpha- and beta-dihydroartemisinin, using post-column alkali decomposition and UV detection is described. Extraction was performed with Bond-Elut Phenyl solid-phase extraction cartridges and analysis by HPLC was carried out using a Waters Symmetry C8 5-microns 150 x 3.9 mm I.D. column. The mobile phase was 50% acetonitrile in 0.1 M acetate buffer (pH 4.8) delivered at a flow-rate of 0.7 ml/min. The column eluate was mixed with 1.2 M potassium hydroxide in 90% methanol delivered at 0.3 ml/min, in a 1-ml reaction coil at 69 degrees C, to form UV-absorbing chromophores which were detected at 290 nm. The recovery of all analytes was greater than 80%. There was no significant difference in the peak-area ratio of alpha- and beta-dihydroartemisinin in plasma. Preliminary pharmacokinetic data from six adult Vietnamese patients who received 120 mg of artesunate by intravenous injection for the treatment of acute falciparum malaria are presented. Despite limited data, the mean half-life of artesunate was approximately 3.5 min while that for dihydroartemisinin was 34 min. These data confirm the relatively rapid clearance of both artesunate and its principle active metabolite, dihydroartemisinin.
Publisher: American Society for Microbiology
Date: 06-2012
DOI: 10.1128/AAC.06232-11
Abstract: Pharmacokinetic differences between piperaquine (PQ) base and PQ tetraphosphate were investigated in 34 Papua New Guinean children aged 5 to 10 years treated for uncomplicated malaria with artemisinin-PQ (ART-PQ) base or dihydroartemisinin-PQ (DHA-PQ) tetraphosphate. Twelve children received ART-PQ base (two daily doses of 3 mg of ART and 18 mg of PQ base as granules/kg of body weight) as recommended by the manufacturer, with regular clinical assessment and blood s ling over 56 days. PQ concentrations in plasma s les collected from 22 children of similar ages with malaria in a previously published pharmacokinetic study of DHA-PQ tetraphosphate (three daily doses of 2.5 mg of ART and 20 mg of PQ tetraphosphate as tablets/kg of body weight) were available for comparison. The disposition of ART was also assessed in the 12 children who received ART-PQ base. Plasma PQ was assayed by high-performance liquid chromatography with UV detection, and ART was assayed using liquid chromatography-mass spectrometry. Multicompartment pharmacokinetic models for PQ and ART were developed using a population-based approach. ART-PQ base was well tolerated, and initial fever abatement and parasite clearance were prompt. There were no differences between the two treatments in the values for the PQ area under the concentration-time curve from time zero to infinity (AUC 0–∞ ), with medians of 49,451 ( n = 12) and 44,556 ( n = 22) μg · h/liter for ART-PQ base and DHA-PQ tetraphosphate, respectively. Recurrent parasitemia was associated with lower PQ exposure. Using a two-compartment ART model, the median AUC 0–∞ was 1,652 μg · h/liter. There was evidence of autoinduction of ART metabolism (relative bioavailability for the second dose, 0.27). These and previously published data suggest that a 3-day ART-PQ base regimen should be further evaluated, in line with World Health Organization recommendations for all artemisinin combination therapies.
Publisher: Wiley
Date: 16-11-2018
DOI: 10.1111/BCP.13775
Publisher: MDPI AG
Date: 03-11-2021
DOI: 10.20944/PREPRINTS202111.0072.V1
Abstract: Because of the need to replace the current clinical artemisinins in artemisinin combination therapies, we are evaluating fitness of amino-artemisinins for this purpose. These include the thiomorpholine derivative artemiside obtained in one scalable synthetic step from dihydroartemisinin (DHA) and the derived sulfone artemisone. We have recently shown that artemiside undergoes facile metabolism via the sulfoxide artemisox into artemisone and thence into the unsaturated metabolite M1 DHA is not a metabolite. Artemisox and M1 are now found to be approximately equipotent with artemiside and artemisone in vitro against asexual P. falciparum (Pf) blood stage parasites (IC50 1.5 & ndash 2.6 nM). Against Pf NF54 blood stage gametocytes, artemisox is potently active (IC50 18.9 nM early-stage, 2.7 nM late-stage). Comparative drug metabolism and pharmacokinetic (DMPK) properties were assessed via po and iv administration of artemiside, artemisox and artemisone in a murine model. Following oral administration, the composite Cmax value of artemiside plus its metabolites artemisox and artemisone formed in vivo is some 2.6-fold higher than that attained following administration of artemisone alone. Given that efficacy of short half-life rapidly-acting antimalarial drugs such as the artemisinins is associated with Cmax, it is apparent that artemiside will be more active than artemisone in vivo, due to additive effects of the metabolites. As is evident from earlier data, artemiside indeed possesses appreciably greater efficacy in vivo against murine malaria. Overall, the higher exposure levels of active drug following administration of artemiside coupled with its synthetic accessibility indicate it is much the preferred drug for incorporation into rational new artemisinin combination therapies.
Publisher: American Society for Microbiology
Date: 10-2014
DOI: 10.1128/AAC.03314-14
Abstract: Coadministration of dihydroartemisinin-piperaquine (DHA-PQ) with fat may improve bioavailability and antimalarial efficacy, but it might also increase toxicity. There have been no studies of these potential effects in the pediatric age group. The tolerability, safety, efficacy, and pharmacokinetics of DHA-PQ administered with or without 8.5 g fat were investigated in 30 Papua New Guinean children aged 5 to 10 years diagnosed with uncomplicated falciparum malaria. Three daily 2.5:11.5-mg-base/kg doses were given with water ( n = 14, group A) or milk ( n = 16, group B), with regular clinical/laboratory assessment and blood s ling over 42 days. Plasma PQ was assayed by high-performance liquid chromatography with UV detection, and DHA was assayed using liquid chromatography-mass spectrometry. Compartmental pharmacokinetic models for PQ and DHA were developed using a population-based approach. DHA-PQ was generally well tolerated, and initial fever and parasite clearance were prompt. There were no differences in the areas under the concentration-time curve (AUC 0–∞ ) for PQ (median, 41,906 versus 36,752 μg · h/liter in groups A and B, respectively P = 0.24) or DHA (4,047 versus 4,190 μg · h/liter P = 0.67). There were also no significant between-group differences in prolongation of the corrected electrocardiographic QT interval (QT c ) initially during follow-up, but the QT c tended to be higher in group B children at 24 h (mean ± standard deviation [SD], 15 ± 10 versus 6 ± 15 ms 0.5 in group A, P = 0.067) and 168 h (10 ± 18 versus 1 ± 23 ms 0.5 , P = 0.24) when plasma PQ concentrations were relatively low. A small amount of fat does not change the bioavailability of DHA-PQ in children, but a delayed persistent effect on ventricular repolarization cannot be excluded.
Publisher: Wiley
Date: 06-2001
DOI: 10.1046/J.1365-2125.2001.01395.X
Abstract: To obtain comprehensive bioavailability data for artesunate (ARTS) and its active metabolite dihydroartemisinin (DHA) following their separate oral administration to Vietnamese volunteers and to patients with acute, uncomplicated falciparum malaria. Volunteers were randomized to receive either i.v. ARTS (120 mg) followed by oral ARTS (150 mg) 8 h later (Group 1, n = 10), or i.v. ARTS (120 mg) followed by oral DHA (120 mg) 8 h later. Patients, also received oral ARTS (150 mg Group 3, n = 8) or DHA (120 mg Group 2, n = 7), in a randomized cross-over study design. Multiple blood s les were collected after each administration and plasma ARTS and/or DHA concentrations were determined by h.p.l.c. Pharmacokinetic descriptors were obtained from noncompartmental analysis and bioavailability was calculated from AUC data. In the patients, the time to 50% parasite clearance (PCT50) and fever clearance time (FCT) also were measured. In Group 1 (volunteers), the mean (95% CI) absolute bioavailability of oral ARTS was 80% (62,98%), while in Group 2 (volunteers), the bioavailability of oral DHA was 45% (34,56%). In the patients (Group 3), the bioavailability of oral DHA relative to oral ARTS was 88% (49,127%). The median PCT50 and FCT were 2.3 and 28 h, respectively. The study shows that the absolute bioavailability of DHA was significantly lower than that for ARTS in healthy volunteers. The bioavailability of ARTS in volunteers was consistent with previous studies in patients with uncomplicated falciparum malaria. The dose-normalized Cmax and AUC(0,infinity) for DHA were significantly greater in patients with falciparum malaria than in healthy volunteers. The high relative bioavailability of DHA in the patients may have been due to lower first-pass clearance. We conclude that, for the treatment of malaria, DHA is likely to be a suitable oral substitute for ARTS. Based on our mean AUC measurements, it appears that equal doses of DHA and ARTS (mg basis) should give equivalent systemic exposure to bioactive DHA in uncomplicated falciparum malaria.
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2017
End Date: 2019
Funder: National Health and Medical Research Council
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End Date: 2019
Funder: National Health and Medical Research Council
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Funder: National Health and Medical Research Council
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End Date: 2019
Funder: National Health and Medical Research Council
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End Date: 2009
Funder: National Health and Medical Research Council
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