51
|
Hughes KR, Biagini GA, Craig AG. Continued cytoadherence of Plasmodium falciparum infected red blood cells after antimalarial treatment. Mol Biochem Parasitol 2009; 169:71-8. [PMID: 19800372 PMCID: PMC2814047 DOI: 10.1016/j.molbiopara.2009.09.007] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2008] [Revised: 09/21/2009] [Accepted: 09/23/2009] [Indexed: 11/02/2022]
Abstract
Development of severe disease in Plasmodium falciparum malaria infection is thought to be, at least in part, due to the sequestration of trophozoite-stage infected red blood cells in the microvasculature. The process of cytoadherence is mediated by binding of the parasite protein PfEMP-1 on the surface of infected red blood cells to endothelial cell receptors. Although antimalarial treatments rapidly kill parasites, significant mortality is still seen in severe malaria, particularly within 24h of hospital admission. We find that cytoadherence of infected red blood cells continues for several hours after killing of the parasite by antimalarials; after 24h treatment using a range of antimalarials binding is approximately one-third the level of untreated parasite cultures. This is consistent with the maintained presence of PfEMP-1 on the surface of drug-treated infected red blood cells. A specific advantage of artesunate over other treatments tested is seen on addition of this drug to younger ring stage parasites, which do not mature to the cytoadherent trophozoite-stage. These findings show that cytoadherence, a potential pathogenic property of P. falciparum infected red blood cells, continues long after the parasite has been killed. These data support the development of adjunctive therapies to reverse the pathophysiological consequences of cytoadherence.
Collapse
Affiliation(s)
- Katie R Hughes
- Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK.
| | | | | |
Collapse
|
52
|
Simpson JA, Jamsen KM, Price RN, White NJ, Lindegardh N, Tarning J, Duffull SB. Towards optimal design of anti-malarial pharmacokinetic studies. Malar J 2009; 8:189. [PMID: 19656413 PMCID: PMC2732628 DOI: 10.1186/1475-2875-8-189] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2009] [Accepted: 08/06/2009] [Indexed: 12/02/2022] Open
Abstract
Background Characterization of anti-malarial drug concentration profiles is necessary to optimize dosing, and thereby optimize cure rates and reduce both toxicity and the emergence of resistance. Population pharmacokinetic studies determine the drug concentration time profiles in the target patient populations, including children who have limited sampling options. Currently, population pharmacokinetic studies of anti-malarial drugs are designed based on logistical, financial and ethical constraints, and prior knowledge of the drug concentration time profile. Although these factors are important, the proposed design may be unable to determine the desired pharmacokinetic profile because there was no formal consideration of the complex statistical models used to analyse the drug concentration data. Methods Optimal design methods incorporate prior knowledge of the pharmacokinetic profile of the drug, the statistical methods used to analyse data from population pharmacokinetic studies, and also the practical constraints of sampling the patient population. The methods determine the statistical efficiency of the design by evaluating the information of the candidate study design prior to the pharmacokinetic study being conducted. Results In a hypothetical population pharmacokinetic study of intravenous artesunate, where the number of patients and blood samples to be assayed was constrained to be 50 and 200 respectively, an evaluation of varying elementary designs using optimal design methods found that the designs with more patients and less samples per patient improved the precision of the pharmacokinetic parameters and inter-patient variability, and the overall statistical efficiency by at least 50%. Conclusion Optimal design methods ensure that the proposed study designs for population pharmacokinetic studies are robust and efficient. It is unethical to continue conducting population pharmacokinetic studies when the sampling schedule may be insufficient to estimate precisely the pharmacokinetic profile.
Collapse
Affiliation(s)
- Julie A Simpson
- Centre for Molecular, Environmental, Genetic and Analytic Epidemiology, School of Population Health, University of Melbourne, Melbourne, Victoria, Australia.
| | | | | | | | | | | | | |
Collapse
|
53
|
Population pharmacokinetics of lumefantrine in pregnant women treated with artemether-lumefantrine for uncomplicated Plasmodium falciparum malaria. Antimicrob Agents Chemother 2009; 53:3837-46. [PMID: 19564366 DOI: 10.1128/aac.00195-09] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Artemether-lumefantrine has become one of the most widely used antimalarial drugs in the world. The objective of this study was to determine the population pharmacokinetic properties of lumefantrine in pregnant women with uncomplicated multidrug-resistant Plasmodium falciparum malaria on the northwestern border of Thailand. Burmese and Karen women (n = 103) with P. falciparum malaria and in the second and third trimesters of pregnancy were treated with artemether-lumefantrine (80/480 mg) twice daily for 3 days. All patients provided five capillary plasma samples for drug quantification, and the collection times were randomly distributed over 14 days. The concentration-time profiles of lumefantrine were assessed by nonlinear mixed-effects modeling. The treatment failure rate (PCR-confirmed recrudescent infections at delivery) was high; 16.5% (95% confidence interval, 9.9 to 25.1). The population pharmacokinetics of lumefantrine were described well by a two-compartment open model with first-order absorption and elimination. The final model included interindividual variability in all pharmacokinetic parameters and a linear covariate relationship between the estimated gestational age and the central volume of distribution. A high proportion of all women (40%, 41/103) had day 7 capillary plasma concentrations of <355 ng/ml (which corresponds to approximately <280 ng/ml in venous plasma), a threshold previously associated with an increased risk of therapeutic failure in nonpregnant patients in this area. Predictive modeling suggests that a twice-daily regimen given for 5 days would be preferable in later pregnancy. In conclusion, altered pharmacokinetic properties of lumefantrine contribute to the high rates of failure of artemether-lumefantrine treatment in later pregnancy. Dose optimization is urgently needed.
Collapse
|
54
|
Efferth T, Romero MR, Wolf DG, Stamminger T, Marin JJG, Marschall M. The antiviral activities of artemisinin and artesunate. Clin Infect Dis 2009; 47:804-11. [PMID: 18699744 DOI: 10.1086/591195] [Citation(s) in RCA: 339] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Traditional Chinese medicine commands a unique position among all traditional medicines because of its 5000 years of history. Our own interest in natural products from traditional Chinese medicine was triggered in the 1990s, by artemisinin-type sesquiterpene lactones from Artemisia annua L. As demonstrated in recent years, this class of compounds has activity against malaria, cancer cells, and schistosomiasis. Interestingly, the bioactivity of artemisinin and its semisynthetic derivative artesunate is even broader and includes the inhibition of certain viruses, such as human cytomegalovirus and other members of the Herpesviridae family (e.g., herpes simplex virus type 1 and Epstein-Barr virus), hepatitis B virus, hepatitis C virus, and bovine viral diarrhea virus. Analysis of the complete profile of the pharmacological activities and molecular modes of action of artemisinin and artesunate and their performance in clinical trials will further elucidate the full antimicrobial potential of these versatile pharmacological tools from nature.
Collapse
Affiliation(s)
- Thomas Efferth
- German Cancer Research Center, Pharmaceutical Biology, Im Neuenheimer Feld 280, Heidelberg, Germany.
| | | | | | | | | | | |
Collapse
|
55
|
Mehlotra RK, Henry-Halldin CN, Zimmerman PA. Application of pharmacogenomics to malaria: a holistic approach for successful chemotherapy. Pharmacogenomics 2009; 10:435-49. [PMID: 19290792 PMCID: PMC2717014 DOI: 10.2217/14622416.10.3.435] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Drug resistance in malaria jeopardizes the most elementary objectives of malaria control--reducing suffering and eliminating mortality. An important, and so far the only known, mechanism of drug resistance appears to be polymorphisms in the malaria parasite genes. Efforts to circumvent antimalarial drug resistance now range from the use of combination therapies with existing agents to genomics-based studies directed toward discovering novel targets and agents. However, the potential contribution of host genetic/molecular factors, particularly those associated with antimalarial drug metabolism, remains largely unexplored. Our knowledge concerning the basic mechanisms involved in the pharmacokinetics of antimalarial drugs is fragmentary. In addition, the link between antimalarial drug pharmacokinetics and treatment outcomes is generally unclear. The purpose of this article is to provide general background information on antimalarial drug resistance and associated parasite genetic factors, and subsequently highlight the aforementioned unexplored and unclear areas, with a view to stimulate much needed further research.
Collapse
Affiliation(s)
- Rajeev K Mehlotra
- Center for Global Health and Diseases, Case Western Reserve University, School of Medicine, Wolstein Research Building #4204, 2103 Cornell Road, Cleveland, OH 44106-7286, USA.
| | | | | |
Collapse
|
56
|
Clark RL, Arima A, Makori N, Nakata Y, Bernard F, Gristwood W, Harrell A, White TEK, Wier PJ. Artesunate: developmental toxicity and toxicokinetics in monkeys. ACTA ACUST UNITED AC 2009; 83:418-34. [PMID: 18702116 DOI: 10.1002/bdrb.20163] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND The developmental toxicity, toxicokinetics, and hematological effects of the antimalarial drug, artesunate, were previously studied in rats and rabbits and have now been studied in cynomolgus monkeys. METHODS Groups of up to 15 pregnant females were dosed on Gestation Days (GD) 20-50 or for 3-7-day intervals. RESULTS At 30 mg/kg/day, 6 embryos died between GD30 and GD40. Histologic examination of 3 live embryos (GD26-GD36) revealed a marked reduction in embryonic erythroblasts and cardiomyopathy. At 12 mg/kg/day, 6 embryos died between GD30 and GD45. Four surviving fetuses examined on GD100 had no malformations, but long bone lengths were slightly decreased. At the developmental no-adverse-effect-level (4 mg/kg/day), maternal plasma AUC was 3.68 ng.h/mL for artesunate and 6.93 ng.h/ml for its active metabolite, dihydroartemisinin (DHA). No developmental toxicity occurred with administration of 12 mg/kg/day for 3 or 7 days, GD29-31 or GD27-33 (maternal plasma AUC of 9.84 ng.h/mL artesunate and 16.4 ng.h/mL DHA). Exposures at embryotoxic doses were substantially lower than human therapeutic exposures. However, differences in monkey and human Vss for artesunate (0.5 L/kg vs. 0.18 L/kg) confound relying solely on AUC for assessing human risk. Decreases in reticulocyte count occur at therapeutic doses in humans. Changes to reticulocyte counts at embryotoxic doses in monkeys (> or =12 mg/kg/day) were variable and generally minor. CONCLUSIONS Artesunate was embryolethal at > or =12 mg/kg/day when dosed for at least 12 days at the beginning of organogenesis, but not when dosed for 3 or 7 days, indicating that developmental toxicity of artesunate is dependent upon duration of dosing in cynomologus monkeys.
Collapse
Affiliation(s)
- Robert L Clark
- GlaxoSmithKline, Upper Merion, Pennsylvania 19406-0939, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
57
|
Mayor A, Serra-Casas E, Bardají A, Sanz S, Puyol L, Cisteró P, Sigauque B, Mandomando I, Aponte JJ, Alonso PL, Menéndez C. Sub-microscopic infections and long-term recrudescence of Plasmodium falciparum in Mozambican pregnant women. Malar J 2009; 8:9. [PMID: 19134201 PMCID: PMC2633011 DOI: 10.1186/1475-2875-8-9] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2008] [Accepted: 01/09/2009] [Indexed: 11/20/2022] Open
Abstract
Background Control of malaria in pregnancy remains a public health challenge. Improvements in its correct diagnosis and the adequacy of protocols to evaluate anti-malarial drug efficacy in pregnancy, are essential to achieve this goal. Methods The presence of Plasmodium falciparum was assessed by real-time (RT) PCR in 284 blood samples from pregnant women with clinical complaints suggestive of malaria, attending the maternity clinic of a Mozambican rural hospital. Parasite recrudescences in 33 consecutive paired episodes during the same pregnancy were identified by msp1 and msp2 genotyping. Results Prevalence of parasitaemia by microscopy was 5.3% (15/284) and 23.2% (66/284) by RT-PCR. Sensitivity of microscopy, compared to RT-PCR detection, was 22.7%. Risk of maternal anaemia was higher in PCR-positive women than in PCR-negative women (odds ratio [OR] = 1.92, 95% confidence interval [CI] 1.09–3.36). Genotyping confirmed that recrudescence after malaria treatment occurred in 7 (21%) out of 33 pregnant women with consecutive episodes during the same pregnancy (time range between recrudescent episodes: 14 to 187 days). Conclusion More accurate and sensitive diagnostic indicators of malaria infection in pregnancy are needed to improve malaria control. Longer follow-up periods than the standard in vivo drug efficacy protocol should be used to assess anti-malarial drug efficacy in pregnancy.
Collapse
Affiliation(s)
- Alfredo Mayor
- Centre de Recerca en Salut Internacional de Barcelona, Hospital Clínic/Institut d'Investigacions Biomèdiques August Pi i Sunyer, Universitat de Barcelona, Rosselló 132, E-08036 Barcelona, Spain.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
58
|
McGready R, Tan SO, Ashley EA, Pimanpanarak M, Viladpai-nguen J, Phaiphun L, Wüstefeld K, Barends M, Laochan N, Keereecharoen L, Lindegardh N, Singhasivanon P, White NJ, Nosten F. A randomised controlled trial of artemether-lumefantrine versus artesunate for uncomplicated plasmodium falciparum treatment in pregnancy. PLoS Med 2008; 5:e253. [PMID: 19265453 PMCID: PMC2605900 DOI: 10.1371/journal.pmed.0050253] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Accepted: 11/12/2008] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND To date no comparative trials have been done, to our knowledge, of fixed-dose artemisinin combination therapies (ACTs) for the treatment of Plasmodium falciparum malaria in pregnancy. Evidence on the safety and efficacy of ACTs in pregnancy is needed as these drugs are being used increasingly throughout the malaria-affected world. The objective of this study was to compare the efficacy, tolerability, and safety of artemether-lumefantrine, the most widely used fixed ACT, with 7 d artesunate monotherapy in the second and third trimesters of pregnancy. METHODS AND FINDINGS An open-label randomised controlled trial comparing directly observed treatment with artemether-lumefantrine 3 d (AL) or artesunate monotherapy 7 d (AS7) was conducted in Karen women in the border area of northwestern Thailand who had uncomplicated P. falciparum malaria in the second and third trimesters of pregnancy. The primary endpoint was efficacy defined as the P. falciparum PCR-adjusted cure rates assessed at delivery or by day 42 if this occurred later than delivery, as estimated by Kaplan-Meier survival analysis. Infants were assessed at birth and followed until 1 y of life. Blood sampling was performed to characterise the pharmacokinetics of lumefantrine in pregnancy. Both regimens were very well tolerated. The cure rates (95% confidence interval) for the intention to treat (ITT) population were: AS7 89.2% (82.3%-96.1%) and AL 82.0% (74.8%-89.3%), p = 0.054 (ITT); and AS7 89.7% (82.6%-96.8%) and AL 81.2% (73.6%-88.8%), p = 0.031 (per-protocol population). One-third of the PCR-confirmed recrudescent cases occurred after 42 d of follow-up. Birth outcomes and infant (up to age 1 y) outcomes did not differ significantly between the two groups. The pharmacokinetic study indicated that low concentrations of artemether and lumefantrine were the main contributors to the poor efficacy of AL. CONCLUSION The current standard six-dose artemether-lumefantrine regimen was well tolerated and safe in pregnant Karen women with uncomplicated falciparum malaria, but efficacy was inferior to 7 d artesunate monotherapy and was unsatisfactory for general deployment in this geographic area. Reduced efficacy probably results from low drug concentrations in later pregnancy. A longer or more frequent AL dose regimen may be needed to treat pregnant women effectively and should now be evaluated. Parasitological endpoints in clinical trials of any antimalarial drug treatment in pregnancy should be extended to delivery or day 42 if it comes later. TRIAL REGISTRATION Current Controlled Trials ISRCTN86353884.
Collapse
Affiliation(s)
- Rose McGready
- Shoklo Malaria Research Unit (SMRU), Mae Sot, Tak, Thailand
- Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Oxford, United Kingdom
- * To whom correspondence should be addressed. E-mail:
| | - Saw Oo Tan
- Shoklo Malaria Research Unit (SMRU), Mae Sot, Tak, Thailand
| | - Elizabeth A Ashley
- Shoklo Malaria Research Unit (SMRU), Mae Sot, Tak, Thailand
- Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Oxford, United Kingdom
| | | | | | - Lucy Phaiphun
- Shoklo Malaria Research Unit (SMRU), Mae Sot, Tak, Thailand
| | | | - Marion Barends
- Shoklo Malaria Research Unit (SMRU), Mae Sot, Tak, Thailand
- Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | | | | | - Niklas Lindegardh
- Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Oxford, United Kingdom
| | | | - Nicholas J White
- Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Oxford, United Kingdom
| | - François Nosten
- Shoklo Malaria Research Unit (SMRU), Mae Sot, Tak, Thailand
- Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Clinical Vaccinology and Tropical Medicine, Churchill Hospital, Oxford, United Kingdom
| |
Collapse
|
59
|
Hong X, Liu CH, Huang XT, Huang TL, Ye SM, Ou WP, Wang NS, Mi SQ. Pharmacokinetics of dihydroartemisinin in Artekin tablets for single and repeated dosing in Chinese healthy volunteers. Biopharm Drug Dispos 2008; 29:237-44. [PMID: 18350560 DOI: 10.1002/bdd.607] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Aim. To study the pharmacokinetics of dihydroartemisinin (DHA) in Artekin (compound dihydroartemisinin) tablets in Chinese healthy volunteers. Methods. Eighteen healthy volunteers (9 males, 9 females) received Artekin tablets for oral administration. The plasma samples of DHA were analysed by liquid-liquid extraction and determined by HPLC/ESI/MS. Results. The plasma DHA concentration-time curves of single dose and repeated doses of DHA were fitted to a two-compartment open model. The mean pharmacokinetic parameters of DHA in a single dose were: t(1/2(beta))=1.245 +/- 0.495 h, C(max)=243.6 +/- 56.15 microg/l, AUC(0 --> infinity)=450 +/- 69 h x microg/l, V(d)=5.75 +/- 2.2 l/kg and Cl=3.245 +/- 0.38 l/h/kg, while in repeated doses they were: t(1/2(beta))=1.085 +/- 0.298 h, AUC(0 --> infinity)=444.35 +/- 80.43 h x ng/ml, V(d)=4.62 +/- 1.128 ml/kg, Cl=3.0125 +/- 0.875 ml/h/kg, respectively. Conclusion. The study showed that DHA in Artekin was rapidly absorbed, distributed and eliminated in the healthy subjects. The pharmacokinetic properties of DHA in Artekin were not affected by gender in a single dose. While in repeated doses accumulation of DHA did not appear after repeated doses.
Collapse
Affiliation(s)
- Xin Hong
- Institute of Clinical Pharmacology, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong Province, PR China
| | | | | | | | | | | | | | | |
Collapse
|
60
|
Li Q, Si Y, Smith KS, Zeng Q, Weina PJ. Embryotoxicity of artesunate in animal species related to drug tissue distribution and toxicokinetic profiles. ACTA ACUST UNITED AC 2008; 83:435-45. [DOI: 10.1002/bdrb.20164] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
61
|
Lee SJ, McGready R, Fernandez C, Stepniewska K, Paw MK, Viladpai-nguen SJ, Thwai KL, Villegas L, Singhasivanon P, Greenwood BM, White NJ, Nosten F. Chloroquine pharmacokinetics in pregnant and nonpregnant women with vivax malaria. Eur J Clin Pharmacol 2008; 64:987-92. [DOI: 10.1007/s00228-008-0500-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Accepted: 04/22/2008] [Indexed: 10/21/2022]
|
62
|
Barnes KI, Watkins WM, White NJ. Antimalarial dosing regimens and drug resistance. Trends Parasitol 2008; 24:127-34. [DOI: 10.1016/j.pt.2007.11.008] [Citation(s) in RCA: 103] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2007] [Revised: 10/18/2007] [Accepted: 11/22/2007] [Indexed: 01/29/2023]
|
63
|
Vallely A, McCarthy J, Changalucha J, Vallely L, Chandramohan D. Treating malaria in pregnancy in developing countries: priorities in clinical research and drug development. Expert Rev Clin Pharmacol 2008; 1:61-72. [PMID: 24410510 DOI: 10.1586/17512433.1.1.61] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Reducing the burden of falciparum malaria in pregnancy is an urgent international public health priority but one that involves considerable challenges. The rapidly declining effectiveness of agents known to be safe in pregnancy, and the limited efficacy, safety and pharmacokinetic data available for many other antimalarial drugs, mean that current options for the treatment of both severe and uncomplicated falciparum malaria in pregnancy are limited. This report summarizes the literature on this subject and recommends drug combinations for evaluation in Phase II/III treatment trials in pregnancy.
Collapse
Affiliation(s)
- Andrew Vallely
- Senior Lecturer, Tropical & Infectious Diseases, University of Queensland, Division of International and Indigenous Health, School of Population Health, Herston Road, Herston, Brisbane Qld 4006, Australia.
| | | | | | | | | |
Collapse
|
64
|
Rogerson SJ, Mwapasa V, Meshnick SR. Malaria in Pregnancy: Linking Immunity and Pathogenesis to Prevention. Am J Trop Med Hyg 2007. [DOI: 10.4269/ajtmh.77.6.suppl.14] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Stephen J. Rogerson
- Department of Medicine (RMH/WH), The University of Melbourne, Royal Melbourne Hospital, Australia; Department of Community Health, College of Medicine, University of Malawi, Blantyre, Malawi; Department of Epidemiology, Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina
| | - Victor Mwapasa
- Department of Medicine (RMH/WH), The University of Melbourne, Royal Melbourne Hospital, Australia; Department of Community Health, College of Medicine, University of Malawi, Blantyre, Malawi; Department of Epidemiology, Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina
| | - Steven R. Meshnick
- Department of Medicine (RMH/WH), The University of Melbourne, Royal Melbourne Hospital, Australia; Department of Community Health, College of Medicine, University of Malawi, Blantyre, Malawi; Department of Epidemiology, Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina
| |
Collapse
|
65
|
Barnes KI, Lindegardh N, Ogundahunsi O, Olliaro P, Plowe CV, Randrianarivelojosia M, Gbotosho GO, Watkins WM, Sibley CH, White NJ. World Antimalarial Resistance Network (WARN) IV: clinical pharmacology. Malar J 2007; 6:122. [PMID: 17822537 PMCID: PMC2014777 DOI: 10.1186/1475-2875-6-122] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2007] [Accepted: 09/06/2007] [Indexed: 12/15/2022] Open
Abstract
A World Antimalarial Resistance Network (WARN) database has the potential to improve the treatment of malaria, through informing current drug selection and use and providing a prompt warning of when treatment policies need changing. This manuscript outlines the contribution and structure of the clinical pharmacology component of this database. The determinants of treatment response are multi-factorial, but clearly providing adequate blood concentrations is pivotal to curing malaria. The ability of available antimalarial pharmacokinetic data to inform optimal dosing is constrained by the small number of patients studied, with even fewer (if any) studies conducted in the most vulnerable populations. There are even less data relating blood concentration data to the therapeutic response (pharmacodynamics). By pooling all available pharmacokinetic data, while paying careful attention to the analytical methodologies used, the limitations of small (and thus underpowered) individual studies may be overcome and factors that contribute to inter-individual variability in pharmacokinetic parameters defined. Key variables for pharmacokinetic studies are defined in terms of patient (or study subject) characteristics, the formulation and route of administration of the antimalarial studied, the sampling and assay methodology, and the approach taken to data analysis. Better defining these information needs and criteria of acceptability of pharmacokinetic-pharmacodynamic (PK-PD) studies should contribute to improving the quantity, relevance and quality of these studies. A better understanding of the pharmacokinetic properties of antimalarials and a more clear definition of what constitutes "therapeutic drug levels" would allow more precise use of the term "antimalarial resistance", as it would indicate when treatment failure is not caused by intrinsic parasite resistance but is instead the result of inadequate drug levels. The clinical pharmacology component of the WARN database can play a pivotal role in monitoring accurately for true antimalarial drug resistance and promptly correcting sub-optimal dosage regimens to prevent these contributing to the emergence and spread of antimalarial resistance.
Collapse
Affiliation(s)
- Karen I Barnes
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa
| | - Niklas Lindegardh
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University. Bangkok Thailand
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Olumide Ogundahunsi
- UNICEF/UNDP/WB/WHO Special Programme for Research & Training in Tropical Diseases, World Health Organisation, Geneva, Switzerland
| | - Piero Olliaro
- UNICEF/UNDP/WB/WHO Special Programme for Research & Training in Tropical Diseases, World Health Organisation, Geneva, Switzerland
| | | | | | - Grace O Gbotosho
- Department of Pharmacology and Therapeutics, College of Medicine, University of Ibadan, Ibadan, Nigeria
| | | | - Carol H Sibley
- Department of Genome Sciences, University of Washington, Seattle, WA, USA
| | - Nicholas J White
- Mahidol Oxford Research Unit, Faculty of Tropical Medicine, Mahidol University. Bangkok Thailand
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| |
Collapse
|
66
|
Abdelrahim II, Adam I, Elghazali G, Gustafsson LL, Elbashir MI, Mirghani RA. Pharmacokinetics of quinine and its metabolites in pregnant Sudanese women with uncomplicated Plasmodium falciparum malaria. J Clin Pharm Ther 2007; 32:15-9. [PMID: 17286785 DOI: 10.1111/j.1365-2710.2007.00788.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES The study was conducted in New Halfa teaching hospital, eastern Sudan to investigate the pharmacokinetics of quinine in pregnant Sudanese women. METHODS Sixteen (eight pregnant and eight non-pregnant) Sudanese women infected with Plasmodium falciparum malaria were given a single dose of quinine hydrochloride (10 mg/kg body weight) as intravenous infusion over 2 h. The women were treated with intramuscular artemether. Plasma was collected before quinine administration and up to 72 h thereafter. These were analysed for quinine and its metabolites, 3-hydroxyquinine, (10R)-10,11-dihydroxyquinine and (10S)-10,11-dihydroxyquinine using high-performance liquid chromatography. RESULTS The two groups were well matched in their basic characteristics. There was no significant difference in the mean maximum plasma concentration attained (C(max)), the mean time at which C(max) was attained, the elimination half-life (t(1/2)) and the total area under the plasma concentration vs. time curve (AUC) of quinine and its metabolites between the pregnant in non-pregnant women. CONCLUSION There was no significant difference in quinine metabolism between pregnant and non-pregnant women and there is no need to adjust quinine dose when treating pregnant women.
Collapse
Affiliation(s)
- I I Abdelrahim
- Faculty of Medicine, University of Khartoum, Khartoum, Sudan
| | | | | | | | | | | |
Collapse
|
67
|
Ward SA, Sevene EJP, Hastings IM, Nosten F, McGready R. Antimalarial drugs and pregnancy: safety, pharmacokinetics, and pharmacovigilance. THE LANCET. INFECTIOUS DISEASES 2007; 7:136-44. [PMID: 17251084 DOI: 10.1016/s1473-3099(07)70025-7] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Before a recommendation for antimalarial drug use in pregnancy is made, it is essential that we understand the potential risks involved and have mechanisms in place to monitor risk during treatment. This requires data on drug disposition during pregnancy and potential toxicological liabilities to the developing fetus and mother. In most cases this information is not available. We review the reproductive toxicology of the main antimalarial drug classes in use or under development. Preclinical data are presented if appropriate, but as human experience overrides such data, in instances in which preclinical studies do not correlate with the human experience the data are reviewed only briefly. Additionally, we highlight the lack of appropriate drug disposition data in pregnancy and suggest mechanisms that can be used to capture data on risk after drug treatment in pregnancy.
Collapse
|
68
|
Vallely A, Vallely L, Changalucha J, Greenwood B, Chandramohan D. Intermittent preventive treatment for malaria in pregnancy in Africa: what's new, what's needed? Malar J 2007; 6:16. [PMID: 17306014 PMCID: PMC1805504 DOI: 10.1186/1475-2875-6-16] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2006] [Accepted: 02/16/2007] [Indexed: 11/26/2022] Open
Abstract
Falciparum malaria is an important cause of maternal, perinatal and neonatal morbidity in high transmission settings in Sub-Saharan Africa. Intermittent preventive treatment with sulphadoxine-pyrimethamine (SP-IPT) has proven efficacious in reducing the burden of pregnancy-associated malaria but increasing levels of parasite resistance mean that the benefits of national SP-IPT programmes may soon be seriously undermined in much of the region. Hence, there is an urgent need to develop alternative drug regimens for IPT in pregnancy. This paper reviews published safety and efficacy data on various antimalarials and proposes several candidate combination regimens for assessment in phase II/III clinical trials.
Collapse
Affiliation(s)
- Andrew Vallely
- National institute for Medical Research, Mwanza Centre, PO Box 1462, Mwanza, Tanzania
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Lisa Vallely
- National institute for Medical Research, Mwanza Centre, PO Box 1462, Mwanza, Tanzania
| | - John Changalucha
- National institute for Medical Research, Mwanza Centre, PO Box 1462, Mwanza, Tanzania
| | - Brian Greenwood
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Daniel Chandramohan
- London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| |
Collapse
|
69
|
Dellicour S, Hall S, Chandramohan D, Greenwood B. The safety of artemisinins during pregnancy: a pressing question. Malar J 2007; 6:15. [PMID: 17300719 PMCID: PMC1802871 DOI: 10.1186/1475-2875-6-15] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2006] [Accepted: 02/14/2007] [Indexed: 12/03/2022] Open
Abstract
Background An increasing number of countries in sub-Saharan Africa are changing to artemisinins combination therapy (ACT) as first or second line treatment for malaria. There is an urgent need to assess the safety of these drugs in pregnant women who may be inadvertently exposed to or actively treated with ACTs. Objectives To examine existing published evidence on the relationship between artemisinin compounds and adverse pregnancy outcomes and consider the published evidence with regard to the safety of these compounds when administered during pregnancy. Methods Studies on ACT use in pregnancy were identified via searches of MEDLINE, EMBASE, Cochrane and Current Contents databases. Data on study characteristics, maternal adverse events, pregnancy outcomes and infant follow up were extracted. Results Fourteen relevant studies (nine descriptive/case reports and five controlled trials) were identified. Numbers of participants in these studies ranged from six to 461. Overall there were reports on 945 women exposed to an artemisinin during pregnancy, 123 in the 1st trimester and 822 in 2nd or 3rd trimesters. The primary end points for these studies were drug efficacy and parasite clearance. Secondary endpoints were birth outcomes including low birth weight, pre-term birth, pregnancy loss, congenital anomalies and developmental milestones. While none of the studies found evidence for an association between the use of artemisinin compounds and increased risk of adverse pregnancy outcomes, none were of sufficient size to detect small differences in event rates that could be of public health importance. Heterogeneity between studies in the artemisinin and comparator drugs used, and in definitions of adverse pregnancy outcomes, limited any pooled analysis. Conclusion The limited data available suggest that artemisinins are effective and unlikely to be cause of foetal loss or abnormalities, when used in late pregnancy. However, none of these studies had adequate power to rule out rare serious adverse events, even in 2nd and 3rd trimesters and there is not enough evidence to effectively assess the risk-benefit profile of artemisinin compounds for pregnant women particularly for 1st trimester exposure. Methodologically rigorous, larger studies and post-marketing pharmacovigilance are urgently required.
Collapse
Affiliation(s)
- Stephanie Dellicour
- Department of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, 50, Bedford Square, London, WC1B 3DP, UK
| | - Susan Hall
- Worldwide Epidemiology, GlaxoSmithKline, Research Triangle Park, NC 27709-3398, USA
| | - Daniel Chandramohan
- Department of Infectious and Tropical Diseases, London School of Hygiene &Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Brian Greenwood
- Department of Infectious and Tropical Diseases, London School of Hygiene &Tropical Medicine, 50, Bedford Square London, WC1B 3DP, UK
| |
Collapse
|
70
|
Nosten F, McGready R, Mutabingwa T. Case management of malaria in pregnancy. THE LANCET. INFECTIOUS DISEASES 2007; 7:118-25. [PMID: 17251082 DOI: 10.1016/s1473-3099(07)70023-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
In all malarious areas, infection by any of the main human plasmodial species during pregnancy is detrimental to the mother and the fetus. These potentially fatal infections must be prevented, but when they develop they require prompt diagnosis and treatment. Current tools to detect malaria parasites in pregnant women are often not used and remain too insensitive to detect a low parasitaemia. The kinetics, safety, and efficacy of available antimalarial drugs are poorly documented because pregnant women are systematically excluded from clinical trials. A considerable effort, involving clinical trials, is urgently required to improve the diagnosis and case management of malaria during pregnancy if the morbidity and mortality of maternal malaria is to be reduced.
Collapse
|
71
|
Mehlotra RK, Bockarie MJ, Zimmerman PA. Prevalence of UGT1A9 and UGT2B7 nonsynonymous single nucleotide polymorphisms in West African, Papua New Guinean, and North American populations. Eur J Clin Pharmacol 2007; 63:1-8. [PMID: 17115150 PMCID: PMC2577308 DOI: 10.1007/s00228-006-0206-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Accepted: 08/31/2006] [Indexed: 11/24/2022]
Abstract
OBJECTIVE UDP-glucuronosyltransferases (UGTs) UGT1A9 and UGT2B7 are involved in the metabolism of antimalarial dihydroartemisinin and antiretroviral zidovudine. Our aim was to analyze the prevalence of UGT1A9 (chromosome 2) and UGT2B7 (chromosome 4) nonsynonymous single nucleotide polymorphisms (SNPs) in West African (WA), Papua New Guinean (PNG), and North American (NA) populations. METHODS Using a post-PCR ligation detection reaction-fluorescent microsphere assay, frequencies of UGT1A9 (8G > A, 98T > C, 766G > A) and UGT2B7 (211G > T, 802C > T, 1192G > A) SNPs were determined in WA (n = 133, 5 countries), PNG (n = 153), and NA (n = 350, 4 ethnic groups) individuals. RESULTS The UGT1A9 variant alleles were not common in the study populations. None of the SNPs were present in WA and PNG. Among NA, all 3 SNPs were present (1% each) in Asian-Americans, while 98T > C was present only in Caucasian-Americans (1%) and Hispanic-Americans (1%). Regarding UGT2B7 SNPs, the prevalence of 802C > T was 21% in WA, 28% in PNG, and 28-52% in NA. The SNP 211G > T was present only in Asian-Americans (9%) and Hispanic-Americans (2%), while 1192G > A was not present in any of the subjects. No significant linkage was observed at UGT1A9, UGT2B7, and between both the loci in any of the study populations. CONCLUSIONS Taken together, the UGT1A9-UGT2B7 polymorphism profile in WA and PNG populations is similar to African-Americans, but different from Asian-Americans. It is important to determine if these differences, along with previously reported differences in cytochrome P450 2B6 allele frequencies, are associated with altered metabolism/effectiveness of artemisinin drugs.
Collapse
Affiliation(s)
- Rajeev K Mehlotra
- Center for Global Health and Diseases, Case Western Reserve University, School of Medicine, Wolstein Research Building #4204, 2103 Cornell Road, Cleveland, OH 44106-7286, USA.
| | | | | |
Collapse
|
72
|
McGready R, Stepniewska K, Lindegardh N, Ashley EA, La Y, Singhasivanon P, White NJ, Nosten F. The pharmacokinetics of artemether and lumefantrine in pregnant women with uncomplicated falciparum malaria. Eur J Clin Pharmacol 2006; 62:1021-31. [PMID: 17053895 DOI: 10.1007/s00228-006-0199-7] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2006] [Accepted: 08/07/2006] [Indexed: 10/24/2022]
Abstract
OBJECTIVE To determine the pharmacokinetic properties of artemether and lumefantrine (AL) in pregnant women with recrudescent uncomplicated multi-drug resistant falciparum malaria. METHODS Pregnant women who had recurrence of parasitaemia following 7 days supervised quinine treatment were treated with AL. Serial blood samples were taken over a 7-day period, and pharmacokinetic parameters were estimated. For lumefantrine, these data were compared in a population pharmacokinetic model with data from non-pregnant, mainly male adults with acute malaria. RESULTS The pregnant women (five in the second trimester and eight in the third trimester) had lower concentrations of artemether, dihydroartemisinin and lumefantrine, and the elimination of lumefantrine in pregnant women was more rapid than reported previously in non-pregnant adults. CONCLUSION Pregnancy is associated with reduced plasma concentrations of both artemether and lumefantrine. This is likely to be of therapeutic significance as plasma concentrations of lumefantrine, after elimination of artemether, are an important determinant of cure. Further studies are needed to determine the optimum dose regimen of artemether-lumefantrine in pregnancy.
Collapse
Affiliation(s)
- Rose McGready
- Shoklo Malaria Research Unit, P.O. Box 46, Mae Sot, Tak, Thailand
| | | | | | | | | | | | | | | |
Collapse
|
73
|
|
74
|
Ashley E, McGready R, Proux S, Nosten F. Malaria. Travel Med Infect Dis 2006; 4:159-73. [PMID: 16887738 DOI: 10.1016/j.tmaid.2005.06.009] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2005] [Accepted: 06/21/2005] [Indexed: 05/11/2023]
Abstract
Malaria is increasing worldwide due to the emergence and spread of drug resistant strains. This poses major health and economic problems for the population living in endemic areas and increases the risk of infections in travelers. The diagnosis of malaria relies on a biological proof of infection by microscopy or with a rapid test. The treatment must be initiated without delay preferably with an artemisinin containing regimen. Uncomplicated malaria can be treated with oral drugs while severe infections will be hospitalized and treated with injectables. Special attention will be given to the most susceptible groups: children and pregnant women.
Collapse
Affiliation(s)
- Elizabeth Ashley
- Shoklo Malaria Research Unit, 68/30 Ban Toong Road, Mae Sot, Tak, 63110 Thailand
| | | | | | | |
Collapse
|