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Wong HN, Padín-Irizarry V, van der Watt ME, Reader J, Liebenberg W, Wiesner L, Smith P, Eribez K, Winzeler EA, Kyle DE, Birkholtz LM, Coertzen D, Haynes RK. Optimal 10-Aminoartemisinins With Potent Transmission-Blocking Capabilities for New Artemisinin Combination Therapies-Activities Against Blood Stage P. falciparum Including PfKI3 C580Y Mutants and Liver Stage P. berghei Parasites. Front Chem 2020; 7:901. [PMID: 31998692 PMCID: PMC6967409 DOI: 10.3389/fchem.2019.00901] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Accepted: 12/13/2019] [Indexed: 12/31/2022] Open
Abstract
We have demonstrated previously that amino-artemisinins including artemiside and artemisone in which an amino group replaces the oxygen-bearing substituents attached to C-10 of the current clinical artemisinin derivatives dihydroartemisinin (DHA), artemether and artesunate, display potent activities in vitro against the asexual blood stages of Plasmodium falciparum (Pf). In particular, the compounds are active against late blood stage Pf gametocytes, and are strongly synergistic in combination with the redox active drug methylene blue. In order to fortify the eventual selection of optimum amino-artemisinins for development into new triple combination therapies also active against artemisinin-resistant Pf mutants, we have prepared new amino-artemisinins based on the easily accessible and inexpensive DHA-piperazine. The latter was converted into alkyl- and aryl sulfonamides, ureas and amides. These derivatives were screened together with the comparator drugs DHA and the hitherto most active amino-artemisinins artemiside and artemisone against asexual and sexual blood stages of Pf and liver stage P. berghei (Pb) sporozoites. Several of the new amino-artemisinins bearing aryl-urea and -amide groups are potently active against both asexual, and late blood stage gametocytes (IC50 0.4-1.0 nM). Although the activities are superior to those of artemiside (IC50 1.5 nM) and artemisone (IC50 42.4 nM), the latter are more active against the liver stage Pb sporozoites (IC50 artemisone 28 nM). In addition, early results indicate these compounds tend not to display reduced susceptibility against parasites bearing the Pf Kelch 13 propeller domain C580Y mutation characteristic of artemisinin-resistant Pf. Thus, the advent of the amino-artemisinins including artemiside and artemisone will enable the development of new combination therapies that by virtue of the amino-artemisinin component itself will possess intrinsic transmission-blocking capabilities and may be effective against artemisinin resistant falciparum malaria.
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Affiliation(s)
- Ho Ning Wong
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom, South Africa
| | - Vivian Padín-Irizarry
- Center for Tropical & Emerging Global Diseases, Coverdell Center, University of Georgia, Athens, GA, United States
| | - Mariëtte E van der Watt
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
| | - Janette Reader
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
| | - Wilna Liebenberg
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom, South Africa
| | - Lubbe Wiesner
- Division of Clinical Pharmacology, Department of Medicine, Groote Schuur Hospital, University of Cape Town, Cape Town, South Africa
| | - Peter Smith
- Division of Clinical Pharmacology, Department of Medicine, Groote Schuur Hospital, University of Cape Town, Cape Town, South Africa
| | - Korina Eribez
- School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Elizabeth A Winzeler
- School of Medicine, University of California, San Diego, La Jolla, CA, United States
| | - Dennis E Kyle
- Center for Tropical & Emerging Global Diseases, Coverdell Center, University of Georgia, Athens, GA, United States
| | - Lyn-Marie Birkholtz
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
| | - Dina Coertzen
- Malaria Parasite Molecular Laboratory, Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Pretoria, South Africa
| | - Richard K Haynes
- Centre of Excellence for Pharmaceutical Sciences, Faculty of Health Sciences, North-West University, Potchefstroom, South Africa
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Resolving neuroinflammation, the therapeutic potential of the anti-malaria drug family of artemisinin. Pharmacol Res 2018; 136:172-180. [DOI: 10.1016/j.phrs.2018.09.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 09/01/2018] [Accepted: 09/04/2018] [Indexed: 12/15/2022]
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Chan WC, Wai Chan DH, Lee KW, Tin WS, Wong HN, Haynes RK. Evaluation and optimization of synthetic routes from dihydroartemisinin to the alkylamino-artemisinins artemiside and artemisone: A test of N-glycosylation methodologies on a lipophilic peroxide. Tetrahedron 2018. [DOI: 10.1016/j.tet.2018.04.027] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Jeeyapant A, Kingston HW, Plewes K, Maude RJ, Hanson J, Herdman MT, Leopold SJ, Ngernseng T, Charunwatthana P, Phu NH, Ghose A, Hasan MMU, Fanello CI, Faiz MA, Hien TT, Day NPJ, White NJ, Dondorp AM. Defining Surrogate Endpoints for Clinical Trials in Severe Falciparum Malaria. PLoS One 2017; 12:e0169307. [PMID: 28052109 PMCID: PMC5215574 DOI: 10.1371/journal.pone.0169307] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 12/14/2016] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Clinical trials in severe falciparum malaria require a large sample size to detect clinically meaningful differences in mortality. This means few interventions can be evaluated at any time. Using a validated surrogate endpoint for mortality would provide a useful alternative allowing a smaller sample size. Here we evaluate changes in coma score and plasma lactate as surrogate endpoints for mortality in severe falciparum malaria. METHODS Three datasets of clinical studies in severe malaria were re-evaluated: studies from Chittagong, Bangladesh (adults), the African 'AQUAMAT' trial comparing artesunate and quinine (children), and the Vietnamese 'AQ' study (adults) comparing artemether with quinine. The absolute change, relative change, slope of the normalization over time, and time to normalization were derived from sequential measurements of plasma lactate and coma score, and validated for their use as surrogate endpoint, including the proportion of treatment effect on mortality explained (PTE) by these surrogate measures. RESULTS Improvements in lactate concentration or coma scores over the first 24 hours of admission, were strongly prognostic for survival in all datasets. In hyperlactataemic patients in the AQ study (n = 173), lower mortality with artemether compared to quinine closely correlated with faster reduction in plasma lactate concentration, with a high PTE of the relative change in plasma lactate at 8 and 12 hours of 0.81 and 0.75, respectively. In paediatric patients enrolled in the 'AQUAMAT' study with cerebral malaria (n = 785), mortality was lower with artesunate compared to quinine, but this was not associated with faster coma recovery. CONCLUSIONS The relative changes in plasma lactate concentration assessed at 8 or 12 hours after admission are valid surrogate endpoints for severe malaria studies on antimalarial drugs or adjuvant treatments aiming at improving the microcirculation. Measures of coma recovery are not valid surrogate endpoints for mortality.
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Affiliation(s)
- Atthanee Jeeyapant
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Hugh W. Kingston
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Charles Darwin University, Darwin, Northern Territory, Australia
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Katherine Plewes
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Richard J. Maude
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Josh Hanson
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Global Health Division, Menzies School of Health Research, Darwin, Australia
| | - M. Trent Herdman
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- University College, Oxford, United Kingdom
| | - Stije J. Leopold
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Thatsanun Ngernseng
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Prakaykaew Charunwatthana
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol Unversity,Bangkok,Thailand
| | - Nguyen Hoan Phu
- Oxford University Clinical Research Unit. Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam
| | - Aniruddha Ghose
- Department of Medicine, Chittagong Medical College Hospital, Chittagong, Bangladesh
| | | | - Caterina I. Fanello
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Kinshasa School of Public Health, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Md Abul Faiz
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Malaria Research Group, Dev Care Foundation, Dhaka, Bangladesh
| | - Tran Tinh Hien
- Oxford University Clinical Research Unit. Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam
| | - Nicholas P. J. Day
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Nicholas J. White
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
| | - Arjen M. Dondorp
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, United Kingdom
- * E-mail:
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Davis TME, Moore BR, Salman S, Page-Sharp M, Batty KT, Manning L. Use of quantitative pharmacology tools to improve malaria treatments. Expert Rev Clin Pharmacol 2015; 9:303-16. [DOI: 10.1586/17512433.2016.1129273] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Carrasquilla G, Barón C, Monsell EM, Cousin M, Walter V, Lefèvre G, Sander O, Fisher LM. Randomized, prospective, three-arm study to confirm the auditory safety and efficacy of artemether-lumefantrine in Colombian patients with uncomplicated Plasmodium falciparum malaria. Am J Trop Med Hyg 2012; 86:75-83. [PMID: 22232454 DOI: 10.4269/ajtmh.2012.11-0192] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The safety of artemether-lumefantrine in patients with acute, uncomplicated Plasmodium falciparum malaria was investigated prospectively using the auditory brainstem response (ABR) and pure-tone thresholds. Secondary outcomes included polymerase chain reaction-corrected cure rates. Patients were randomly assigned in a 3:1:1 ratio to either artemether-lumefantrine (N = 159), atovaquone-proguanil (N = 53), or artesunate-mefloquine (N = 53). The null hypothesis (primary outcome), claiming that the percentage of patients with a baseline to Day-7 ABR Wave III latency increase of > 0.30 msec is ≥ 15% after administration of artemether-lumefantrine, was rejected; 2.6% of patients (95% confidence interval: 0.7-6.6) exceeded 0.30 msec, i.e., significantly below 15% (P < 0.0001). A model-based analysis found no apparent relationship between drug exposure and ABR change. In all three groups, average improvements (2-4 dB) in pure-tone thresholds were observed, and polymerase chain reaction-corrected cure rates were > 95% to Day 42. The results support the continued safe and efficacious use of artemether-lumefantrine in uncomplicated falciparum malaria.
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Medana IM, Day NPJ, Sachanonta N, Mai NTH, Dondorp AM, Pongponratn E, Hien TT, White NJ, Turner GDH. Coma in fatal adult human malaria is not caused by cerebral oedema. Malar J 2011; 10:267. [PMID: 21923924 PMCID: PMC3182981 DOI: 10.1186/1475-2875-10-267] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 09/17/2011] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND The role of brain oedema in the pathophysiology of cerebral malaria is controversial. Coma associated with severe Plasmodium falciparum malaria is multifactorial, but associated with histological evidence of parasitized erythrocyte sequestration and resultant microvascular congestion in cerebral vessels. To determine whether these changes cause breakdown of the blood-brain barrier and resultant perivascular or parenchymal cerebral oedema, histology, immunohistochemistry and image analysis were used to define the prevalence of histological patterns of oedema and the expression of specific molecular pathways involved in water balance in the brain in adults with fatal falciparum malaria. METHODS The brains of 20 adult Vietnamese patients who died of severe malaria were examined for evidence of disrupted vascular integrity. Immunohistochemistry and image analysis was performed on brainstem sections for activation of the vascular endothelial growth factor (VEGF) receptor 2 and expression of the aquaporin 4 (AQP4) water channel protein. Fibrinogen immunostaining was assessed as evidence of blood-brain barrier leakage and perivascular oedema formation. Correlations were performed with clinical, biochemical and neuropathological parameters of severe malaria infection. RESULTS The presence of oedema, plasma protein leakage and evidence of VEGF signalling were heterogeneous in fatal falciparum malaria and did not correlate with pre-mortem coma. Differences in vascular integrity were observed between brain regions with the greatest prevalence of disruption in the brainstem, compared to the cortex or midbrain. There was a statistically non-significant trend towards higher AQP4 staining in the brainstem of cases that presented with coma (P = .02). CONCLUSIONS Histological evidence of cerebral oedema or immunohistochemical evidence of localised loss of vascular integrity did not correlate with the occurrence of pre-mortem coma in adults with fatal falciparum malaria. Enhanced expression of AQP4 water channels in the brainstem may, therefore, reflect a mix of both neuropathological or attempted neuroprotective responses to oedema formation.
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Affiliation(s)
- Isabelle M Medana
- Nuffield Department of Clinical Laboratory Sciences, The John Radcliffe Hospital, University of Oxford, Oxford, UK
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Meningeal inflammation increases artemether concentrations in cerebrospinal fluid in Papua New Guinean children treated with intramuscular artemether. Antimicrob Agents Chemother 2011; 55:5027-33. [PMID: 21859936 DOI: 10.1128/aac.00375-11] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Although the artemisinin-associated neurotoxicity identified in vitro and in animal studies has not been confirmed clinically, only one adult study has measured cerebrospinal fluid (CSF) concentrations after administration of conventional doses. Potential artemisinin neurotoxicity could be serious in children, especially those with meningitis and, consequently, a compromised blood-brain barrier. We measured CSF/plasma artemether and dihydroartemisinin (DHA) concentrations in 32 Papua New Guinean children with a mean age of 39 months with suspected or proven severe falciparum malaria who underwent a single lumbar puncture after intramuscular artemether administration. CSF artemether concentrations were 0 to 43.5 μg/liter and CSF concentration/plasma concentration ratios were 0 to 38.1%. DHA was measurable in CSF in only two children. The seven children with meningeal inflammation (CSF white cell count > 20/mm(3)) had higher CSF artemether concentration/plasma artemether concentration ratios than those without (median, 6.7% [interquartile ratio, 2.5 to 27.8%]% versus 0.0% [interquartile ratio, 0.0 to 2.5%]; P = 0.002). Meningeal inflammation was associated with a 4.6-fold increase in the CSF artemether concentration/plasma artemether concentration ratio in a population pharmacokinetic model. These data suggest that pharmacovigilance should be heightened when intramuscular artemether is given to severely ill children with evidence of meningeal inflammation.
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A golden phoenix arising from the herbal nest — A review and reflection on the study of antimalarial drug Qinghaosu. ACTA ACUST UNITED AC 2010. [DOI: 10.1007/s11458-010-0214-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Artemisinin-based combination therapies and their introduction in Japan. J Infect Chemother 2010; 16:375-82. [DOI: 10.1007/s10156-010-0077-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2010] [Indexed: 10/19/2022]
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Medana IM, Day NPJ, Hien TT, White NJ, Turner GDH. Erythropoietin and its receptors in the brainstem of adults with fatal falciparum malaria. Malar J 2009; 8:261. [PMID: 19930602 PMCID: PMC2785829 DOI: 10.1186/1475-2875-8-261] [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: 06/24/2009] [Accepted: 11/22/2009] [Indexed: 12/14/2022] Open
Abstract
Background Facilitation of endogenous neuroprotective pathways, such as the erythropoietin (Epo) pathway, has been proposed as adjuvant treatment strategies in cerebral malaria. Whether different endogenous protein expression levels of Epo or differences in the abundance of its receptor components could account for the extent of structural neuropathological changes or neurological complications in adults with severe malaria was investigated. Methods High sensitivity immunohistochemistry was used to assess the frequency, distribution and concordance of Epo and components of its homodimeric and heteromeric receptors, Epo receptor and CD131, within the brainstem of adults who died of severe malaria. The following relationships with Epo and its receptor components were also defined: (i) sequestration and indicators of hypoxia; (ii) vascular damage in the form of plasma protein leakage and haemorrhage; (iii) clinical complications and neuropathological features of severe malaria disease. Brainstems of patients dying in the UK from unrelated non-infectious causes were examined for comparison. Results The incidence of endogenous Epo in parenchymal brain cells did not greatly differ between severe malaria and non-neurological UK controls at the time of death. However, EpoR and CD131 labelling of neurons was greater in severe malaria compared with non-neurological controls (P = .009). EpoR labelling of vessels was positively correlated with admission peripheral parasite count (P = .01) and cerebral sequestration (P < .0001). There was a strong negative correlation between arterial oxygen saturation and EpoR labelling of glia (P = .001). There were no significant correlations with indicators of vascular damage, neuronal chromatolysis, axonal swelling or vital organ failure. Conclusion Cells within the brainstem of severe malaria patients showed protein expression of Epo and its receptor components. However, the incidence of endogeneous expression did not reflect protection from vascular or neuronal injury, and/or clinical manifestations, such as coma. These findings do not provide support for Epo as an adjuvant neuroprotective agent in adults with severe malaria.
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Affiliation(s)
- Isabelle M Medana
- Nuffield Department of Clinical Laboratory Sciences, The John Radcliffe Hospital, University of Oxford, Oxford, UK.
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Ambler MT, Dubowitz LM, Arunjerdja R, Hla EP, Thwai KL, Viladpainguen J, Singhasivanon P, Luxemburger C, Nosten F, McGready R. The neurological assessment in young children treated with artesunate monotherapy or artesunate-mefloquine combination therapy for uncomplicated Plasmodium falciparum malaria. Malar J 2009; 8:207. [PMID: 19725966 PMCID: PMC2743706 DOI: 10.1186/1475-2875-8-207] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2009] [Accepted: 09/02/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Mefloquine and artesunate combination therapy is the recommended first-line treatment for uncomplicated malaria throughout much of south-east Asia. Concerns have been raised about the potential central nervous system (CNS) effects of both drug components and there are no detailed reports in very young children. METHODS Children, aged between three months and five years, with acute uncomplicated Plasmodium falciparum malaria were randomized to either 7 days of artesunate monotherapy or the same schedule of artesunate plus mefloquine on day 7 and 8. Neurological testing targeting coordination and behaviour was carried out at day 0, 7, 9, 10, 14 and 28. Non-febrile healthy control children from the same population were tested on days 0, 7, 14 and 28. RESULTS From December 1994 to July 1997, 91 children with uncomplicated P. falciparum, 45 treated with artesunate monotherapy, 46 treated with mefloquine and artesunate combination therapy and 36 non-febrile controls, underwent neurological testing. Malaria and fever had a significant negative impact on testing performance. By contrast, the anti-malarial treatments were not associated with worsening performances in the various components of the test. Artesunate and mefloquine do not appear to have a significant influence on coordination and behaviour. Children treated with mefloquine were significantly less likely to suffer recurrent malaria infection during follow-up compared to those treated with artesunate alone (P = 0.033). CONCLUSION In keeping with the results of randomized controlled trials in adults, mefloquine was not associated with a decrease in specific items of neurological performance. Likewise, children treated with artesunate did not perform significantly differently to control children. This study does not exclude subtle or rare treatment CNS effects of artesunate or mefloquine. Treatment of acute uncomplicated malaria results in a significant improvement on items of neurological performance.
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Affiliation(s)
- Michael T Ambler
- Shoklo Malaria Research Unit, PO Box 46, Mae Sot, Tak, Thailand.
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Kumar V, Mahajan A, Chibale K. Synthetic medicinal chemistry of selected antimalarial natural products. Bioorg Med Chem 2008; 17:2236-75. [PMID: 19157883 DOI: 10.1016/j.bmc.2008.10.072] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2008] [Revised: 07/28/2008] [Accepted: 10/31/2008] [Indexed: 11/25/2022]
Abstract
Natural products remain a rich source of novel molecular scaffolds for novel antimalarial agents in the fight against malaria. This has been well demonstrated in the case of quinine and artemisinin both of which have served as templates for the development of structurally simpler analogues that either served or continue to serve as effective antimalarials. This review will expound on these two natural products as well as other selected natural products that have served either as antimalarial agents or as potential lead compounds in the development of antimalarial drugs.
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Affiliation(s)
- Vipan Kumar
- Department of Chemistry, University of Cape Town, Private Bag, Rondebosh 7701, South Africa
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Gürkov R, Eshetu T, Miranda IB, Berens-Riha N, Mamo Y, Girma T, Krause E, Schmidt M, Hempel JM, Löscher T. Ototoxicity of artemether/lumefantrine in the treatment of falciparum malaria: a randomized trial. Malar J 2008; 7:179. [PMID: 18796142 PMCID: PMC2559845 DOI: 10.1186/1475-2875-7-179] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Accepted: 09/16/2008] [Indexed: 12/02/2022] Open
Abstract
Background Due to increasing drug resistance, artemisinin-based combination chemotherapy (ACT) has become the first-line treatment of falciparum malaria in many endemic countries. However, irreversible ototoxicity associated with artemether/lumefantrine (AL) has been reported recently and suggested to be a serious limitation in the use of ACT. The aim of the study was to compare ototoxicity, tolerability, and efficacy of ACT with that of quinine and atovaquone/proguanil in the treatment of uncomplicated falciparum malaria. Methods Ninety-seven patients in south-west Ethiopia with slide-confirmed malaria were randomly assigned to receive either artemether/lumefantrine or quinine or atovaquone/proguanil and followed-up for 90 days. Comprehensive audiovestibular testing by pure tone audiometry (PTA), transitory evoked (TE) and distortion product (DP) otoacoustic emissions (OAE) and brain stem evoked response audiometry (BERA) was done before enrolment and after seven, 28 and 90 days. Results PTA and DP-OAE levels revealed transient significant cochlear hearing loss in patients treated with quinine but not in those treated with artemether/lumefantrine or atovaquone/proguanil. TE-OAE could be elicited in all examinations, except for three patients in the Q group on day 7, who suffered a transient hearing loss greater than 30 dB. There was no evidence of drug-induced brain stem lesions by BERA measurements. Conclusion There was no detrimental effect of a standard oral regimen of artemether/lumefantrine on peripheral hearing or brainstem auditory pathways in patients with uncomplicated falciparum malaria. In contrast, transient hearing loss is common after quinine therapy and due to temporary outer hair cell dysfunction.
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Affiliation(s)
- Robert Gürkov
- Department of Otorhinolaryngology Head and Neck Surgery, Ludwig Maximilians University, Munich, Germany.
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Deen JL, von Seidlein L, Dondorp A. Therapy of uncomplicated malaria in children: a review of treatment principles, essential drugs and current recommendations. Trop Med Int Health 2008; 13:1111-30. [DOI: 10.1111/j.1365-3156.2008.02117.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Busari OA, Oligbu G. Chorea in a 29-year-old Nigerian following antimalarial treatment with artesunate. Int J Infect Dis 2007; 12:221-3. [PMID: 18069028 DOI: 10.1016/j.ijid.2007.06.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2007] [Revised: 06/15/2007] [Accepted: 06/19/2007] [Indexed: 11/27/2022] Open
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Affiliation(s)
- Nicholas Day
- Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand, and the Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
| | - Arjen M. Dondorp
- Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand, and the Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, John Radcliffe Hospital, University of Oxford, Oxford, United Kingdom
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Checkley AM, Whitty CJM. Artesunate, artemether or quinine in severe Plasmodium falciparum malaria? Expert Rev Anti Infect Ther 2007; 5:199-204. [PMID: 17402835 DOI: 10.1586/14787210.5.2.199] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Quinine and the artemisinin-derivative drugs artesunate and artemether are effective treatments for severe falciparum malaria. Trials comparing artemether with quinine have not demonstrated convincing evidence of a mortality advantage for artemether. The South East Asian Quinine Artesunate Malaria Trial (SEAQUAMAT), a multicenter, randomized, open-label trial in 1461 adults with severe malaria in Asia compared artesunate with quinine. Mortality was 15% in the artesunate group and 22% in the quinine group, a reduction of 34.7% (95% confidence interval: 18.5-47.6%) in the artesunate group, with almost all the benefit reported in those with high parasite counts. Artesunate should constitute first-line treatment for severe malaria in Asia. These results can probably be generalized to the treatment of severe malaria in adults from all areas, especially in those with hyperparasitemia. However, it is unclear whether these results can be generalized to children in Africa, who constitute the majority of those who die from severe malaria worldwide.
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Affiliation(s)
- Anna M Checkley
- SpR Infectious Diseases, The Hospital for Tropical Diseases, Mortimer Market Centre, Capper St., London, WC1E 6AU, UK.
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22
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Toovey S. Are currently deployed artemisinins neurotoxic? Toxicol Lett 2006; 166:95-104. [PMID: 16828992 DOI: 10.1016/j.toxlet.2006.06.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Revised: 05/31/2006] [Accepted: 06/01/2006] [Indexed: 01/25/2023]
Abstract
In vitro, animal, and human clinical studies suggest currently deployed artemisinins possess neurotoxic potential. A specific and consistent pattern of brainstem injuries that includes auditory processing centers has been reported from all laboratory animals studied. Hearing loss, ataxia, and tremor are reported from humans. Neurotoxicity appears mediated in part through artemisinin induced oxidative stress in exposed brainstems. In vitro studies suggest that artemisinin neurotoxicity does not manifest immediately upon exposure, but that once commenced it is inevitable and irreversible; extrapolation from in vitro data suggests that 14 days may possibly be required for full development, casting doubt upon some animal safety studies and human necropsy studies. Uncertainty remains over the neurotoxicity of currently deployed artemisinins, and their safety profile should be reviewed, especially in pediatric use. The development of non-neurotoxic artemisinins is possible and should be encouraged.
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Affiliation(s)
- Stephen Toovey
- Royal Free and University College Medical School, London, UK; Travel Clinic, Cape Town, South Africa.
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23
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Newton PN, Day NPJ, White NJ. Misattribution of central nervous system dysfunction to artesunate. Clin Infect Dis 2006; 41:1687-8; author reply 1688. [PMID: 16267750 DOI: 10.1086/498033] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Idro R, Jenkins NE, Newton CRJC. Pathogenesis, clinical features, and neurological outcome of cerebral malaria. Lancet Neurol 2006; 4:827-40. [PMID: 16297841 DOI: 10.1016/s1474-4422(05)70247-7] [Citation(s) in RCA: 313] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Cerebral malaria is the most severe neurological complication of Plasmodium falciparum malaria. Even though this type of malaria is most common in children living in sub-Saharan Africa, it should be considered in anybody with impaired consciousness that has recently travelled in a malaria-endemic area. Cerebral malaria has few specific features, but there are differences in clinical presentation between African children and non-immune adults. Subsequent neurological impairments are also most common and severe in children. Sequestration of infected erythrocytes within cerebral blood vessels seems to be an essential component of the pathogenesis. However, other factors such as convulsions, acidosis, or hypoglycaemia can impair consciousness. In this review, we describe the clinical features and epidemiology of cerebral malaria. We highlight recent insights provided by ex-vivo work on sequestration and examination of pathological specimens. We also summarise recent studies of persisting neurocognitive impairments in children who survive cerebral malaria and suggest areas for further research.
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Affiliation(s)
- Richard Idro
- Centre for Geographic Medicine Research-Coast, Kenya Medical Research Insitute, Kilifi, Kenya.
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25
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Bray PG, Ward SA, O'Neill PM. Quinolines and artemisinin: chemistry, biology and history. Curr Top Microbiol Immunol 2005; 295:3-38. [PMID: 16265885 DOI: 10.1007/3-540-29088-5_1] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Plasmodium falciparum is the most important parasitic pathogen in humans, causing hundreds of millions of malaria infections and millions of deaths each year. At present there is no effective malaria vaccine and malaria therapy is totally reliant on the use of drugs. New drugs are urgently needed because of the rapid evolution and spread of parasite resistance to the current therapies. Drug resistance is one of the major factors contributing to the resurgence of malaria, especially resistance to the most affordable drugs such as chloroquine. We need to fully understand the antimalarial mode of action of the existing drugs and the way that the parasite becomes resistant to them in order to design and develop the new therapies that are so urgently needed. In respect of the quinolines and artemisinins, great progress has been made recently in studying the mechanisms of drug action and drug resistance in malaria parasites. Here we summarize from a historical, biological and chemical, perspective the exciting new advances that have been made in the study of these important antimalarial drugs.
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Affiliation(s)
- P G Bray
- Division of Molecular and Biochemical Parasitology, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, UK.
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26
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Abstract
Artemisinins were discovered to be highly effective antimalarial drugs shortly after the isolation of the parent artemisinin in 1971 in China. These compounds combine potent, rapid antimalarial activity with a wide therapeutic index and an absence of clinically important resistance. Artemisinin containing regimens meet the urgent need to find effective treatments for multidrug resistant malaria and have recently been advocated for widespread deployment. Comparative trials of artesunate and quinine for severe malaria are in progress to see if the persistently high mortality of this condition can be reduced.
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Affiliation(s)
- C J Woodrow
- Department of Cellular and Molecular Medicine, Infectious Diseases, St George's Hospital Medical School, Tooting, London, UK
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27
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Karunajeewa HA, Ilett KF, Dufall K, Kemiki A, Bockarie M, Alpers MP, Barrett PH, Vicini P, Davis TME. Disposition of artesunate and dihydroartemisinin after administration of artesunate suppositories in children from Papua New Guinea with uncomplicated malaria. Antimicrob Agents Chemother 2004; 48:2966-72. [PMID: 15273107 PMCID: PMC478493 DOI: 10.1128/aac.48.8.2966-2972.2004] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2004] [Revised: 03/15/2004] [Accepted: 04/16/2004] [Indexed: 11/20/2022] Open
Abstract
A detailed pharmacokinetic analysis was performed with 47 children from Papua New Guinea with uncomplicated falciparum or vivax malaria treated with artesunate (ARTS) suppositories (Rectocaps) given in two doses of approximately 13 mg/kg of body weight 12 h apart. Following an intensive sampling protocol, samples were assayed for ARTS and its primary active metabolite, dihydroartemisinin (DHA), by liquid chromatography-mass spectrometry. A population pharmacokinetic model was developed to describe the data. Following administration of the first dose, the mean maximal concentrations of ARTS and DHA were 1,085 nmol/liter at 0.9 h and 2,525 nmol/liter at 2.3 h, respectively. The absorption half-life for ARTS was 2.3 h, and the conversion half-life (ARTS to DHA) was 0.27 h, while the elimination half-life of DHA was 0.71 h. The mean common volumes of distribution for ARTS and DHA relative to bioavailability were 42.8 and 2.04 liters/kg, respectively, and the mean clearance values relative to bioavailability were 6 and 2.2 liters/h/kg for ARTS and DHA, respectively. Substantial interpatient variability was observed, and the bioavailability of the second dose relative to that of the first was estimated to be 0.72. The covariates age, sex, and alpha-thalassemia genotype were not influential in the pharmacokinetic model development; but the inclusion of weight as a covariate significantly improved the performance of the model. An ARTS suppositories dose of 10 of 20 mg/kg is appropriate for use in children with uncomplicated malaria.
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Affiliation(s)
- Harin A Karunajeewa
- School of Medicine and Pharmacology, University of Western Australia, Crawley, Australia
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28
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Berman J. Toxicity of commonly-used antimalarial drugs. Travel Med Infect Dis 2004; 2:171-84. [PMID: 17291978 DOI: 10.1016/j.tmaid.2004.02.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2004] [Accepted: 02/02/2004] [Indexed: 10/26/2022]
Affiliation(s)
- Jonathan Berman
- Office of Clinical and Regulatory Affairs, National Center for Complementary and Alternative Medicine, National Institutes of Health, 6707 Democracy Boulevard, Suite 401, Bethesda, MD 20892, USA
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29
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Toovey S, Jamieson A. Audiometric changes associated with the treatment of uncomplicated falciparum malaria with co-artemether. Trans R Soc Trop Med Hyg 2004; 98:261-7; discussion 268-9. [PMID: 15109547 DOI: 10.1016/j.trstmh.2003.11.001] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2003] [Revised: 11/01/2003] [Accepted: 11/12/2003] [Indexed: 11/30/2022] Open
Abstract
Animal studies have demonstrated artemisinin brain stem toxicity with auditory centres being especially affected; there has, to date, been no evidence of such toxicity with oral artemisinins in humans. Subjects working at a construction site in Mozambique had audiometric assessments taken on joining and leaving the project. Subjects with uncomplicated malarias received co-artemether (artemether-lumefantrine) (n = 150) while age-, gender-, weight- and race-matched controls (n = 150) neither suffered malaria nor received antimalarial therapy. Hearing thresholds were measured at predefined frequencies in treated subjects and controls. Subjects receiving co-artemether had a significantly greater heating loss than controls at all frequencies except 250 Hz and 500 Hz (P values ranging from <0.001 to 0.04, Mann-Whitney U). Mean changes at the different frequencies in subjects ranged from -6.50 dB (95% CI -8.19 to -4.81) [at 1kHz frequency] to -0.07 dB (95% CI -2.19 to 2.05) [at 6 kHz frequency]. Mean changes in the control group ranged from -4.20 dB (95% CI -5.97 to -2.43) [at 1 kHz frequency] to +2.7 dB (95% CI -0.93 to 4.47) [at 6 kHz frequency]. Treatment of uncomplicated malaria with co-artemether is associated with hearing loss, possibly from synergy between potentially ototoxic agents in combination. The safety and neurotoxicity of artemesinins and other endoperoxides needs to be more fully evaluated.
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Affiliation(s)
- Stephen Toovey
- SAA-Netcare Travel Clinics, South Africa and Mozambique, P.O. Box 786692, Sandton, 2146, South Africa.
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Abstract
A discrepancy seems to prevail with regard to the toxicity and safety of the artemisinin family of antimalarials. While these compounds have been found to be virtually void of any serious side effects in humans, their neurotoxicity in animal models has raised concerns about their use. In this paper, we present selected examples of both pre-clinical and clinical studies dealing with adverse effects of artemisinin drugs. We suggest that the prolonged presence of artemisinins upon slow release from oil-based intramuscular formulations is the main cause of the observed toxicity in laboratory animals. In contrast, oral intake of these compounds, which is by far the most common formulation used for treatment of malaria patients, results in rapid clearance of these drugs and is thus unlikely to cause any toxicity in human subjects. Another plausible factor may be the relatively high doses of artemisinin compounds used in animal studies. In conclusion, the observation of the toxicity of artemisinin compounds in animals, but not in humans, is most likely due to different pharmacokinetic profiles after different routes of administrations.
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Affiliation(s)
- Toufigh Gordi
- Department of Pharmaceutics, School of Pharmacy, State University of New York at Buffalo, Buffalo, NY 14260, USA.
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