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Yang X, Zhang B, Wang S, Lu Y, Chen K, Luo C, Sun A, Zhang H. OTTM: an automated classification tool for translational drug discovery from omics data. Brief Bioinform 2023; 24:bbad301. [PMID: 37594310 PMCID: PMC10516341 DOI: 10.1093/bib/bbad301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 07/22/2023] [Accepted: 07/31/2023] [Indexed: 08/19/2023] Open
Abstract
Omics data from clinical samples are the predominant source of target discovery and drug development. Typically, hundreds or thousands of differentially expressed genes or proteins can be identified from omics data. This scale of possibilities is overwhelming for target discovery and validation using biochemical or cellular experiments. Most of these proteins and genes have no corresponding drugs or even active compounds. Moreover, a proportion of them may have been previously reported as being relevant to the disease of interest. To facilitate translational drug discovery from omics data, we have developed a new classification tool named Omics and Text driven Translational Medicine (OTTM). This tool can markedly narrow the range of proteins or genes that merit further validation via drug availability assessment and literature mining. For the 4489 candidate proteins identified in our previous proteomics study, OTTM recommended 40 FDA-approved or clinical trial drugs. Of these, 15 are available commercially and were tested on hepatocellular carcinoma Hep-G2 cells. Two drugs-tafenoquine succinate (an FDA-approved antimalarial drug targeting CYC1) and branaplam (a Phase 3 clinical drug targeting SMN1 for the treatment of spinal muscular atrophy)-showed potent inhibitory activity against Hep-G2 cell viability, suggesting that CYC1 and SMN1 may be potential therapeutic target proteins for hepatocellular carcinoma. In summary, OTTM is an efficient classification tool that can accelerate the discovery of effective drugs and targets using thousands of candidate proteins identified from omics data. The online and local versions of OTTM are available at http://otter-simm.com/ottm.html.
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Affiliation(s)
- Xiaobo Yang
- ShanghaiTech University
- School of Life Science and Technology, ShanghaiTech University, 393 Huaxiazhong Road, Shanghai 200031, China
| | - Bei Zhang
- Shanghai Institute of Materia Medica
- Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, China
| | - Siqi Wang
- Beijing Proteome Research Center
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, and National Center for Protein Sciences (Beijing)
| | - Ye Lu
- Nanjing University of Chinese Medicine
- School of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing 210023, China; Chemical Biology Research Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | - Kaixian Chen
- academician medicinal scientist of the Chinese Academy of Sciences
- Drug Discovery and Design Center, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China; School of Life Science and Technology, ShanghaiTech University, 393 Huaxiazhong Road, Shanghai 200031, China; School of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Cheng Luo
- Shanghai Institute of Materia Medica
- Chemical Biology Research Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China; University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, China; School of Chinese Materia Medica, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Aihua Sun
- Beijing Proteome Research Center
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences (Beijing), Beijing Institute of Lifeomics; Research Unit of Proteomics-driven Cancer Precision Medicine, Chinese Academy of Medical Sciences
| | - Hao Zhang
- Shanghai Institute of Materia Medica
- Chemical Biology Research Center, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zuchongzhi Road, Shanghai 201203, China
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Ravindar L, Hasbullah SA, Rakesh KP, Hassan NI. Recent developments in antimalarial activities of 4-aminoquinoline derivatives. Eur J Med Chem 2023; 256:115458. [PMID: 37163950 DOI: 10.1016/j.ejmech.2023.115458] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 04/26/2023] [Accepted: 05/04/2023] [Indexed: 05/12/2023]
Abstract
Malaria is the fifth most lethal parasitic infection in the world. Antimalarial medications have played a crucial role in preventing and eradicating malaria. Numerous heterocyclic moieties have been incorporated into the creation of effective antimalarial drugs. The 4-aminoquinoline moiety is favoured in antimalarial drug discovery due to the diverse biological applications of its derivative. Since the 1960s, 4-aminoquinoline has been an important antimalarial drug due to its low toxicity, high tolerability, and rapid absorption after administration. This review focused on the antimalarial efficacy of the 4-aminoquinoline moiety hybridised with various heterocyclic scaffolds developed by scientists since 2018 against diverse Plasmodium clones. It could aid in the future development of more effective antimalarial agents.
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Affiliation(s)
- Lekkala Ravindar
- Department of Chemical Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), Bangi, 43600, Selangor, Malaysia
| | - Siti Aishah Hasbullah
- Department of Chemical Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), Bangi, 43600, Selangor, Malaysia
| | - K P Rakesh
- Department of Radiology, Biomedical Research Imaging Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Nurul Izzaty Hassan
- Department of Chemical Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), Bangi, 43600, Selangor, Malaysia.
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Fernandes VDS, da Rosa R, Zimmermann LA, Rogério KR, Kümmerle AE, Bernardes LSC, Graebin CS. Antiprotozoal agents: How have they changed over a decade? Arch Pharm (Weinheim) 2021; 355:e2100338. [PMID: 34661935 DOI: 10.1002/ardp.202100338] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 09/29/2021] [Accepted: 09/30/2021] [Indexed: 12/21/2022]
Abstract
Neglected tropical diseases are a diverse group of communicable diseases that are endemic in low- or low-to-middle-income countries located in tropical and subtropical zones. The number and availability of drugs for treating these diseases are low, the administration route is inconvenient in some cases, and most of them have safety, efficacy, or adverse/toxic reaction issues. The need for developing new drugs to deal with these issues is clear, but one of the most drastic consequences of this negligence is the lack of interest in the research and development of new therapeutic options among major pharmaceutical companies. Positive changes have been achieved over the last few years, although the overall situation remains alarming. After more than one decade since the original work reviewing antiprotozoal agents came to light, now it is time to question ourselves: How has the scenario for the treatment of protozoal diseases such as malaria, leishmaniasis, human African trypanosomiasis, and American trypanosomiasis changed? This review covers the last decade in terms of the drugs currently available for the treatment of these diseases as well as the clinical candidates being currently investigated.
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Affiliation(s)
- Vitória de Souza Fernandes
- Department of Pharmaceutical Sciences, Pharmaceutical and Medicinal Chemistry Laboratory, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Rafael da Rosa
- Department of Organic Chemistry, Medicinal Chemistry and Molecular Diversity Laboratory, Federal Rural University of Rio de Janeiro, Seropédica, Rio de Janeiro, Brazil
| | - Lara A Zimmermann
- Department of Organic Chemistry, Medicinal Chemistry and Molecular Diversity Laboratory, Federal Rural University of Rio de Janeiro, Seropédica, Rio de Janeiro, Brazil
| | - Kamilla R Rogério
- Department of Pharmaceutical Sciences, Pharmaceutical and Medicinal Chemistry Laboratory, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Arthur E Kümmerle
- Department of Pharmaceutical Sciences, Pharmaceutical and Medicinal Chemistry Laboratory, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil
| | - Lilian S C Bernardes
- Department of Organic Chemistry, Medicinal Chemistry and Molecular Diversity Laboratory, Federal Rural University of Rio de Janeiro, Seropédica, Rio de Janeiro, Brazil
| | - Cedric S Graebin
- Department of Pharmaceutical Sciences, Pharmaceutical and Medicinal Chemistry Laboratory, Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil
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Ahmad SS, Rahi M, Sharma A. Relapses of Plasmodium vivax malaria threaten disease elimination: time to deploy tafenoquine in India? BMJ Glob Health 2021; 6:bmjgh-2020-004558. [PMID: 33619041 PMCID: PMC7903102 DOI: 10.1136/bmjgh-2020-004558] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Revised: 01/30/2021] [Accepted: 02/02/2021] [Indexed: 12/21/2022] Open
Affiliation(s)
- Sundus Shafat Ahmad
- Parasite and Host Biology, National Institute of Malaria Research, New Delhi, Delhi, India
| | - Manju Rahi
- Epidemiology and Communicable Diseases, Indian Council of Medical Research, New Delhi, Delhi, India
| | - Amit Sharma
- Parasite and Host Biology, National Institute of Malaria Research, New Delhi, Delhi, India
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Rodrigo C, Rajapakse S, Fernando D. Tafenoquine for preventing relapse in people with Plasmodium vivax malaria. Cochrane Database Syst Rev 2020; 9:CD010458. [PMID: 32892362 PMCID: PMC8094590 DOI: 10.1002/14651858.cd010458.pub3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
BACKGROUND Plasmodium vivax malaria has a persistent liver stage that causes relapse of the disease and continued P vivax transmission. Primaquine (PQ) is used to clear the liver stage of the parasite, but treatment is required for 14 days. Primaquine also causes haemolysis in people with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Tafenoquine (TQ) is a new alternative to PQ with a longer half-life and can be used as a single-dose treatment. OBJECTIVES To assess the effects of tafenoquine 300 mg (single dose) on preventing P vivax relapse. SEARCH METHODS We searched the following up to 3 June 2020: the Cochrane Infectious Diseases Group Specialized Register; CENTRAL; MEDLINE; Embase; and three other databases. We also searched the WHO International Clinical Trial Registry Platform and the metaRegister of Controlled Trials for ongoing trials using "tafenoquine" and "malaria" as search terms up to 3 June 2020. SELECTION CRITERIA Randomized controlled trials (RCTs) that gave TQ to prevent relapse in people with P vivax malaria. We planned to include trials irrespective of whether participants had been screened for G6PD enzyme deficiency. DATA COLLECTION AND ANALYSIS All review authors independently extracted data and assessed risk of bias. As true relapse and reinfection are difficult to differentiate in people living in endemic areas, studies report "recurrences" of infection as a proxy for relapse. We carried out meta-analysis where appropriate, and gave estimates as risk ratios (RR) with 95% confidence intervals (CI). We assessed the certainty of the evidence using the GRADE approach. MAIN RESULTS Three individually randomized RCTs met our inclusion criteria, all in endemic areas, and thus reporting recurrence. Trials compared TQ with PQ or placebo, and all participants received chloroquine (CQ) to treat the asexual infection). In all trials, pregnant and G6PD-deficient people were excluded. Tafenoquine 300 mg single dose versus no treatment for relapse prevention Two trials assessed this comparison. TQ 300 mg single dose reduces P vivax recurrences compared to no antihypnozoite treatment during a six-month follow-up, but there is moderate uncertainty around effect size (RR 0.32, 95% CI 0.12 to 0.88; 2 trials, 504 participants; moderate-certainty evidence). In people with normal G6PD status, there is probably little or no difference in any type of adverse events (2 trials, 504 participants; moderate-certainty evidence). However, we are uncertain if TQ causes more serious adverse events (2 trials, 504 participants; very low-certainty evidence). Both RCTs reported a total of 23 serious adverse events in TQ groups (One RCT reported 21 events) and a majority (15 events) were a drop in haemoglobin level by > 3g/dl (or >30% reduction from baseline). Tafenoquine 300 mg single dose versus primaquine 15 mg/day for 14 days for relapse prevention Three trials assessed this comparison. There is probably little or no difference between TQ and PQ in preventing recurrences (proxy measure for relapse) up to six months of follow-up (RR 1.04, 95% CI 0.8 to 1.34; 3 trials, 747 participants; moderate-certainty evidence). In people with normal G6PD status, there is probably little or no difference in any type of adverse events (3 trials, 747 participants; moderate-certainty evidence). We are uncertain if TQ can cause more serious adverse events compared to PQ (3 trials, 747 participants; very low-certainty evidence). Two trials had higher point estimates against TQ while the other showed the reverse. Most commonly reported serious adverse event in TQ group was a decline in haemoglobin level (19 out of 29 events). Some other serious adverse events, though observed in the TQ group, are unlikely to be caused by it (Hepatitis E infection, limb abscess, pneumonia, menorrhagia). AUTHORS' CONCLUSIONS TQ 300 mg single dose prevents relapses after clinically parasitologically confirmed P vivax malaria compared to no antihypnozoite treatment, and with no difference detected in studies comparing it to PQ to date. However, the inability to differentiate a true relapse from a recurrence in the available studies may affect these estimates. The drug is untested in children and in people with G6PD deficiency. Single-dose treatment is an important practical advantage compared to using PQ for the same purpose without an overall increase in adverse events in non-pregnant, non-G6PD-deficient adults.
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Affiliation(s)
- Chaturaka Rodrigo
- Department of Pathology, School of Medical Sciences, University of New South Wales, Sydney, Australia
| | - Senaka Rajapakse
- Department of Clinical Medicine, Faculty of Medicine, University of Colombo, Colombo, Sri Lanka
| | - Deepika Fernando
- Department of Parasitology, Faculty of Medicine, University of Colombo, Colombo, Sri Lanka
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Lobo AMG, Magalhães IRS. Determination of tafenoquine in human plasma by dispersive liquid‐liquid microextraction. SEPARATION SCIENCE PLUS 2020. [DOI: 10.1002/sscp.201900088] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Amanda M. G. Lobo
- Faculdade de Ciências FarmacêuticasUniversidade Federal do Amazonas Manaus Amazonas Brazil
| | - Igor R. S. Magalhães
- Faculdade de Ciências FarmacêuticasUniversidade Federal do Amazonas Manaus Amazonas Brazil
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Abstract
The scientific community worldwide has realized that malaria elimination will not be possible without development of safe and effective transmission-blocking interventions. Primaquine, the only WHO recommended transmission-blocking drug, is not extensively utilized because of the toxicity issues in G6PD deficient individuals. Therefore, there is an urgent need to develop novel therapeutic interventions that can target malaria parasites and effectively block transmission. But at first, it is imperative to unravel the existing portfolio of transmission-blocking drugs. This review highlights transmission-blocking potential of current antimalarial drugs and drugs that are in various stages of clinical development. The collective analysis of the relationships between the structure and the activity of transmission-blocking drugs is expected to help in the design of new transmission-blocking antimalarials.
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Gopi G, Behera SM, Behera P. Tafenoquine: A Breakthrough Drug for Radical Cure and Elimination of Malaria. EXPLORATORY RESEARCH AND HYPOTHESIS IN MEDICINE 2019; X:1-6. [DOI: 10.14218/erhm.2019.00004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Hounkpatin AB, Kreidenweiss A, Held J. Clinical utility of tafenoquine in the prevention of relapse of Plasmodium vivax malaria: a review on the mode of action and emerging trial data. Infect Drug Resist 2019; 12:553-570. [PMID: 30881061 PMCID: PMC6411314 DOI: 10.2147/idr.s151031] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Tafenoquine is an 8-aminoquinoline with activity against all human life cycle stages of Plasmodium vivax, including dormant liver stages – so called hypnozoites. Its long half-life of ~15 days is allowing for a single exposure regimen. It has been under development since 1980 and received approval by the US Food and Drug Administration in summer 2018 as an anti-relapse drug for P. vivax malaria in patients aged 16 years and older and for prophylaxis of malaria caused by any Plasmodium species in adults. Prior to tafenoquine administration, glucose-6-phosphate dehydrogenase (G6PD) deficiency needs to be excluded by testing. Individuals with a deficient G6PD activity are at risk of tafenoquine-induced hemolysis – as is the case for primaquine, the mainstay drug for P. vivax radical cure. A wealth of clinical studies have been conducted and are still ongoing to assess the safety, tolerability, and efficacy of tafenoquine. This review focuses on data emerging from the latest clinical trials on P. vivax radical cure with tafenoquine, the key studies for regulatory approval of tafenoquine, and elucidates the latest hypothesis on the mode of action.
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Affiliation(s)
- Aurore B Hounkpatin
- Institute of Tropical Medicine, Eberhard Karls University Tübingen, Tübingen, Germany, .,German Centre for Infection Research, Partner Site Tübingen, Tübingen, Germany, .,Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon,
| | - Andrea Kreidenweiss
- Institute of Tropical Medicine, Eberhard Karls University Tübingen, Tübingen, Germany, .,German Centre for Infection Research, Partner Site Tübingen, Tübingen, Germany,
| | - Jana Held
- Institute of Tropical Medicine, Eberhard Karls University Tübingen, Tübingen, Germany, .,German Centre for Infection Research, Partner Site Tübingen, Tübingen, Germany, .,Centre de Recherches Médicales de Lambaréné (CERMEL), Lambaréné, Gabon,
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Rout S, Mahapatra RK. Plasmodium falciparum: Multidrug resistance. Chem Biol Drug Des 2019; 93:737-759. [DOI: 10.1111/cbdd.13484] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Revised: 01/05/2019] [Accepted: 01/09/2019] [Indexed: 12/25/2022]
Affiliation(s)
- Subhashree Rout
- School of BiotechnologyKIIT University Bhubaneswar Odisha India
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Das S, Dielschneider R, Chanas-LaRue A, Johnston JB, Gibson SB. Antimalarial drugs trigger lysosome-mediated cell death in chronic lymphocytic leukemia (CLL) cells. Leuk Res 2018; 70:79-86. [PMID: 29902707 DOI: 10.1016/j.leukres.2018.06.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 06/04/2018] [Accepted: 06/06/2018] [Indexed: 01/12/2023]
Abstract
Lysosomes are the most acidic vesicles within mammalian cells and are promising targets for the treatment of breast cancer, glioblastomas and acute myeloid leukemia (AML). Our previous studies have shown that chronic lymphocytic leukemia (CLL) cells are also sensitive to lysosome disruption and cell death, by siramesine or chemotherapy. In the present study, we screened the antimalarial drugs, mefloquine, atovaquone, primaquine, and tafenoquine, for their effects on lysosome disruption and cytotoxicity in primary CLL cells. We found that mefloquine and tafenoquine could permeabilize lysosome membranes and induce cell death at doses that are clinically achievable. In contrast, these agents had less effect on normal B cells. Tafenoquine was most effective at inducing cell death, and this was associated with increased formation of reactive oxygen species (ROS) and lipid peroxidation. Addition of ROS scavengers blocked both tafenoquine- and mefloquine-induced cell death. Moreover, blocking the activity of cathepsins released from the lysosomes decreased tafenoquine-induced cell death. Taken together, lysosome disruption using antimalarial drugs is a novel approach for the treatment of CLL.
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Affiliation(s)
- Subhadip Das
- Research Institute of Oncology and Hematology, CancerCare Manitoba, Winnipeg, Manitoba, Canada
| | - Rebecca Dielschneider
- Research Institute of Oncology and Hematology, CancerCare Manitoba, Winnipeg, Manitoba, Canada; Department of Immunology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Aaron Chanas-LaRue
- Research Institute of Oncology and Hematology, CancerCare Manitoba, Winnipeg, Manitoba, Canada; Department of Immunology, University of Manitoba, Winnipeg, Manitoba, Canada
| | - James B Johnston
- Research Institute of Oncology and Hematology, CancerCare Manitoba, Winnipeg, Manitoba, Canada; Department of Internal Medicine, University of Manitoba, Winnipeg, Manitoba, Canada
| | - Spencer B Gibson
- Research Institute of Oncology and Hematology, CancerCare Manitoba, Winnipeg, Manitoba, Canada; Department of Immunology, University of Manitoba, Winnipeg, Manitoba, Canada; Department of Biochemistry and Medical Genetics, University of Manitoba, Winnipeg, Manitoba, Canada.
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Baird JK. Tafenoquine for travelers' malaria: evidence, rationale and recommendations. J Travel Med 2018; 25:5150129. [PMID: 30380095 PMCID: PMC6243017 DOI: 10.1093/jtm/tay110] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 10/17/2018] [Accepted: 10/30/2018] [Indexed: 01/01/2023]
Abstract
Background Endemic malaria occurring across much of the globe threatens millions of exposed travelers. While unknown numbers of them suffer acute attacks while traveling, each year thousands return from travel and become stricken in the weeks and months following exposure. This represents perhaps the most serious, prevalent and complex problem faced by providers of travel medicine services. Since before World War II, travel medicine practice has relied on synthetic suppressive blood schizontocidal drugs to prevent malaria during exposure, and has applied primaquine for presumptive anti-relapse therapy (post-travel or post-diagnosis of Plasmodium vivax) since 1952. In 2018, the US Food and Drug Administration approved the uses of a new hepatic schizontocidal and hypnozoitocidal 8-aminoquinoline called tafenoquine for the respective prevention of all malarias and for the treatment of those that relapse (P. vivax and Plasmodium ovale). Methods The evidence and rationale for tafenoquine for the prevention and treatment of malaria was gathered by means of a standard search of the medical literature along with the package inserts for the tafenoquine products Arakoda™ and Krintafel™ for the prevention of all malarias and the treatment of relapsing malarias, respectively. Results The development of tafenoquine-an endeavor of 40 years-at last brings two powerful advantages to travel medicine practice against the malaria threat: (i) a weekly regimen of causal prophylaxis; and (ii) a single-dose radical cure for patients infected by vivax or ovale malarias. Conclusions Although broad clinical experience remains to be gathered, tafenoquine appears to promise more practical and effective prevention and treatment of malaria. Tafenoquine thus applied includes important biological and clinical complexities explained in this review, with particular regard to the problem of hemolytic toxicity in G6PD-deficient patients.
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Affiliation(s)
- J Kevin Baird
- Eijkman-Oxford Clinical Research Unit, Eijkman Institute of Molecular Biology, Jakarta 10430, Indonesia; and Nuffield Department of Medicine, the Centre for Tropical Medicine and Global Health, University of Oxford, UK
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Fukuda MM, Krudsood S, Mohamed K, Green JA, Warrasak S, Noedl H, Euswas A, Ittiverakul M, Buathong N, Sriwichai S, Miller RS, Ohrt C. A randomized, double-blind, active-control trial to evaluate the efficacy and safety of a three day course of tafenoquine monotherapy for the treatment of Plasmodium vivax malaria. PLoS One 2017; 12:e0187376. [PMID: 29121061 PMCID: PMC5679603 DOI: 10.1371/journal.pone.0187376] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2017] [Accepted: 10/09/2017] [Indexed: 12/19/2022] Open
Abstract
Background Tafenoquine is an investigational 8-aminoquinoline for the prevention of Plasmodium vivax relapse. Tafenoquine has a long half-life and the potential for more convenient dosing, compared with the currently recommended 14-day primaquine regimen. Methods This randomized, active-control, double-blind trial was conducted in Bangkok, Thailand. Seventy patients with microscopically confirmed P. vivax were randomized (2:1) to tafenoquine 400 mg once daily for 3 days or 2500 mg total dose chloroquine phosphate (1500 mg chloroquine base) given over 3 days plus primaquine 15 mg daily for 14 days. Patients were followed to day 120. Results Day 28 adequate clinical response rate in the per-protocol population was 93% (40/43) (90%CI 83–98%) with tafenoquine, and 100% (22/22) (90%CI 87–100%) with chloroquine/primaquine. Day 120 relapse prevention was 100% (35/35) with tafenoquine (90%CI 92–100%), and 95% (19/20) (90%CI 78–100%) with chloroquine/primaquine. Mean (SD) parasite, gametocyte and fever clearance times with tafenoquine were 82.5 h (32.3), 49.1 h (33.0), and 41.1 h (31.4) versus 40.0 h (15.7), 22.7 h (16.4), and 24.7 h (17.7) with chloroquine/primaquine, respectively. Peak methemoglobin was 1.4–25.6% (median 7.4%, mean 9.1%) in the tafenoquine arm, and 0.5–5.9% (median 1.5%, mean 1.9%) in the chloroquine/primaquine arm. There were no clinical symptoms of methemoglobinemia in any patient. Discussion Although there was no difference in efficacy in this study, the slow rate of parasite, gametocyte and fever clearance indicates that tafenoquine should not be used as monotherapy for radical cure of P. vivax malaria. Also, monotherapy increases the potential risk of resistance developing to this long-acting agent. Clinical trials of single-dose tafenoquine 300 mg combined with standard 3-day chloroquine or artemisinin-based combination therapy are ongoing. Trial registration Clinicaltrials.gov NCT01290601
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Affiliation(s)
- Mark M. Fukuda
- Armed Forces Research Institute of Medical Science, Bangkok, Thailand
- * E-mail:
| | | | - Khadeeja Mohamed
- GlaxoSmithKline Research and Development, Uxbridge, Middlesex, United Kingdom
| | - Justin A. Green
- GlaxoSmithKline Research and Development, Uxbridge, Middlesex, United Kingdom
| | | | - Harald Noedl
- Armed Forces Research Institute of Medical Science, Bangkok, Thailand
| | - Ataya Euswas
- Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
| | - Mali Ittiverakul
- Armed Forces Research Institute of Medical Science, Bangkok, Thailand
| | - Nillawan Buathong
- Armed Forces Research Institute of Medical Science, Bangkok, Thailand
| | | | - R. Scott Miller
- Armed Forces Research Institute of Medical Science, Bangkok, Thailand
| | - Colin Ohrt
- Walter Reed Army Institute of Research, Silver Spring, Maryland, United States of America
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Ley B, Bancone G, von Seidlein L, Thriemer K, Richards JS, Domingo GJ, Price RN. Methods for the field evaluation of quantitative G6PD diagnostics: a review. Malar J 2017; 16:361. [PMID: 28893237 PMCID: PMC5594530 DOI: 10.1186/s12936-017-2017-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 09/06/2017] [Indexed: 01/12/2023] Open
Abstract
Individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency are at risk of severe haemolysis following the administration of 8-aminoquinoline compounds. Primaquine is the only widely available 8-aminoquinoline for the radical cure of Plasmodium vivax. Tafenoquine is under development with the potential to simplify treatment regimens, but point-of-care (PoC) tests will be needed to provide quantitative measurement of G6PD activity prior to its administration. There is currently a lack of appropriate G6PD PoC tests, but a number of new tests are in development and are likely to enter the market in the coming years. As these are implemented, they will need to be validated in field studies. This article outlines the technical details for the field evaluation of novel quantitative G6PD diagnostics such as sample handling, reference testing and statistical analysis. Field evaluation is based on the comparison of paired samples, including one sample tested by the new assay at point of care and one sample tested by the gold-standard reference method, UV spectrophotometry in an established laboratory. Samples can be collected as capillary or venous blood; the existing literature suggests that potential differences in capillary or venous blood are unlikely to affect results substantially. The collection and storage of samples is critical to ensure preservation of enzyme activity, it is recommended that samples are stored at 4 °C and testing occurs within 4 days of collection. Test results can be visually presented as scatter plot, Bland-Altman plot, and a histogram of the G6PD activity distribution of the study population. Calculating the adjusted male median allows categorizing results according to G6PD activity to calculate standard performance indicators and to perform receiver operating characteristic (ROC) analysis.
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Affiliation(s)
- Benedikt Ley
- 0000 0000 8523 7955grid.271089.5Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Australia
| | - Germana Bancone
- 0000 0004 1937 0490grid.10223.32Shoklo Malaria Research Unit, Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Mae Sot, Thailand ,0000 0004 1936 8948grid.4991.5Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
| | | | - Kamala Thriemer
- 0000 0000 8523 7955grid.271089.5Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Australia
| | - Jack S. Richards
- 0000 0001 2224 8486grid.1056.2Malaria Elimination Program, Burnet Institute, Melbourne, VIC Australia ,0000 0001 2179 088Xgrid.1008.9Department of Medicine, University of Melbourne, Parkville, VIC Australia ,Victorian Infectious Diseases Service, Peter Doherty Institute for Infection and Immunity, Melbourne, VIC Australia
| | - Gonzalo J. Domingo
- 0000 0000 8940 7771grid.415269.dDiagnostics Global Program, PATH, Seattle, WA USA
| | - Ric N. Price
- 0000 0000 8523 7955grid.271089.5Global and Tropical Health Division, Menzies School of Health Research and Charles Darwin University, Darwin, Australia ,0000 0004 1936 8948grid.4991.5Centre for Tropical Medicine and Global Health, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK
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16
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[Role of primaquine in malaria control and elimination in French-speaking Africa]. BULLETIN DE LA SOCIETE DE PATHOLOGIE EXOTIQUE (1990) 2017; 110:198-206. [PMID: 28417346 DOI: 10.1007/s13149-017-0556-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 12/05/2016] [Indexed: 12/20/2022]
Abstract
Primaquine, an 8-aminoquinoline, is a relatively unknown and underutilized drug in French-speaking African countries. It acts against the liver stage parasites of all human malaria species, asexual blood stages of Plasmodium vivax and, to a lesser degree, Plasmodium falciparum; P. falciparum mature gametocytes, and P. vivax and Plasmodium ovale hypnozoites. Gastrointestinal disturbances are its most common side effects. The clinical utility of primaquine is limited due to its hematological side effects in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency and other contraindications (pregnant woman, breastfeeding woman, infants less than 6 months old). In the light of the recent recommendations of the World Health Organization (WHO), we propose to examine how primaquine can be used in French-speaking Africa to improve malaria control and move towards malaria elimination. Two indications supported by the WHO are of relevance in Africa. First, artemisinin-based combination therapies and primaquine given as a single low dose (0.25 mg base/kg) are effective to kill asexual and sexual parasites of P. falciparum, are well-tolerated, and have very little risk even in mild to moderate G6PD-deficient patients. This strategy may be helpful to contain transmission in an area in Africa where P. falciparum malaria incidence has decreased considerably. There is an ethical concern in administering primaquine as a gametocytocide as it does not confer any direct benefit to the treated patient. However, the single low-dose primaquine is most likely associated with very low risk for adverse hematological effects, and WHO recommends its use even without prior G6PD testing. In our opinion, clinical studies including G6PD test should be conducted to assess the safety of low-dose primaquine in African patients. Second, primaquine is effective and necessary for radical treatment of P. vivax and P. ovale, but the standard 14-day treatment (0.25-0.5 mg base/kg/day) is not recommended in patients with G6PD deficiency. Prior G6PD testing is required before prescribing primaquine for radical treatment. The use of primaquine for radical treatment in patients without contraindications does not raise any major ethical problem since the probability of relapse in patients who do not receive anti-hypnozoite treatment can be relatively high and each relapse can cause or aggravate anemia, especially in children. In our opinion, patients with mild or moderate G6PD deficiency should not be treated with primaquine at present. Further clinical studies are necessary to define the role of this drug for radical treatment in G6PD-deficient African patients. Without primaquine, the eventual elimination of P. vivax and P. ovale malaria appears to be very difficult. Updated epidemiological data on G6PD, Duffy antigen, and the current distribution of and burden due to P. vivax and P. ovale are required for a rational use of primaquine in the African continent. Moreover, clinical studies on primaquine are required in Africa.
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Kemirembe K, Cabrera M, Cui L. Interactions between tafenoquine and artemisinin-combination therapy partner drug in asexual and sexual stage Plasmodium falciparum. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2017; 7:131-137. [PMID: 28319724 PMCID: PMC5358947 DOI: 10.1016/j.ijpddr.2017.03.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 03/04/2017] [Accepted: 03/08/2017] [Indexed: 12/18/2022]
Abstract
The 8-aminoquinoline tafenoquine (TFQ), a primaquine derivative, is currently in late-stage clinical development for the radical cure of P. vivax. Here drug interactions between TFQ and chloroquine and six artemisinin-combination therapy (ACT) partner drugs in P. falciparum asexual stages and gametocytes were investigated. TFQ was mostly synergistic with the ACT-partner drugs in asexual parasites regardless of genetic backgrounds. However, at fixed ratios of 1:3, 1:1 and 3:1, TFQ only interacted synergistically with naphthoquine, pyronaridine and piperaquine in gametocytes. This study indicated that TFQ and ACT-partner drugs will likely have increased potency against asexual stages of the malaria parasites, whereas some drugs may interfere with each other against the P. falciparum gametocytes.
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Affiliation(s)
- Karen Kemirembe
- Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Mynthia Cabrera
- Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA
| | - Liwang Cui
- Department of Entomology, The Pennsylvania State University, University Park, PA 16802, USA.
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Artesunate-tafenoquine combination therapy promotes clearance and abrogates transmission of the avian malaria parasite Plasmodium gallinaceum. Vet Parasitol 2017; 233:97-106. [DOI: 10.1016/j.vetpar.2016.12.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 12/02/2016] [Accepted: 12/12/2016] [Indexed: 11/24/2022]
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Milner EE, Berman J, Caridha D, Dickson SP, Hickman M, Lee PJ, Marcsisin SR, Read LT, Roncal N, Vesely BA, Xie LH, Zhang J, Zhang P, Li Q. Cytochrome P450 2D-mediated metabolism is not necessary for tafenoquine and primaquine to eradicate the erythrocytic stages of Plasmodium berghei. Malar J 2016; 15:588. [PMID: 27923405 PMCID: PMC5142148 DOI: 10.1186/s12936-016-1632-8] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 11/22/2016] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Due to the ability of the 8-aminoquinolines (8AQs) to kill different stages of the malaria parasite, primaquine (PQ) and tafenoquine (TQ) are vital for causal prophylaxis and the eradication of erythrocytic Plasmodium sp. parasites. Recognizing the potential role of cytochrome (CYP) 450 2D6 in the metabolism and subsequent hepatic efficacy of 8-aminoquinolines, studies were designed to explore whether CYP2D-mediated metabolism was related to the ability of single-dose PQ and TQ to eliminate the asexual and sexual erythrocytic stages of Plasmodium berghei. METHODS An IV P. berghei sporozoite murine challenge model was utilized to directly compare causal prophylactic and erythrocytic activity (asexual and sexual parasite stages) dose-response relationships in C57BL/6 wild-type (WT) mice and subsequently compare the erythrocytic activity of PQ and TQ in WT and CYP2D knock-out (KO) mice. RESULTS Single-dose administration of either 25 mg/kg TQ or 40 mg/kg PQ eradicated the erythrocytic stages (asexual and sexual) of P. berghei in C57BL WT and CYP2D KO mice. In WT animals, the apparent elimination of hepatic infections occurs at lower doses of PQ than are required to eliminate erythrocytic infections. In contrast, the minimally effective dose of TQ needed to achieve causal prophylaxis and to eradicate erythrocytic parasites was analogous. CONCLUSION The genetic deletion of the CYP2D cluster does not affect the ability of PQ or TQ to eradicate the blood stages (asexual and sexual) of P. berghei after single-dose administration.
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Affiliation(s)
- Erin E Milner
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA.
| | - Jonathan Berman
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Diana Caridha
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Samuel P Dickson
- United States Army Medical Materiel Development Authority (USAMMDA), Ft Detrick, Frederick, MD, USA
| | - Mark Hickman
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Patricia J Lee
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Sean R Marcsisin
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Lisa T Read
- United States Army Medical Materiel Development Authority (USAMMDA), Ft Detrick, Frederick, MD, USA
| | - Norma Roncal
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Brian A Vesely
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Lisa H Xie
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Jing Zhang
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Ping Zhang
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
| | - Qigui Li
- Walter Reed Army Institute of Research (WRAIR), Silver Spring, MD, USA
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20
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Mischlinger J, Agnandji ST, Ramharter M. Single dose treatment of malaria - current status and perspectives. Expert Rev Anti Infect Ther 2016; 14:669-78. [PMID: 27254098 DOI: 10.1080/14787210.2016.1192462] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
INTRODUCTION Despite increased international efforts for control and ultimate elimination, malaria remains a major health problem. Currently, artemisinin-based combination therapies are the treatment of choice for uncomplicated malaria exhibiting high efficacy in clinical trial settings in sub-Saharan Africa. However, their administration over a three-day period is associated with important problems of treatment adherence resulting in markedly reduced effectiveness of currently recommended antimalarials under real world settings. AREAS COVERED Antimalarial drug candidates and antimalarial drug combinations currently under advanced clinical development for the indication as single dose antimalarial therapy. Expert commentary: Several new drug candidates and combinations are currently undergoing pivotal proof-of-concept studies or clinical development programmes. The development of a single dose combination therapy would constitute a breakthrough in the control of malaria. Such an innovative treatment approach would simultaneously close the effectiveness gap of current three-day therapies and revolutionize population based interventions in the context of malaria elimination campaigns.
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Affiliation(s)
- Johannes Mischlinger
- a Centre de Recherches Médicales de Lambaréné , Lambaréné , Gabon.,b Institut für Tropenmedizin , Universität Tübingen , Tübingen , Germany
| | - Selidji T Agnandji
- a Centre de Recherches Médicales de Lambaréné , Lambaréné , Gabon.,b Institut für Tropenmedizin , Universität Tübingen , Tübingen , Germany
| | - Michael Ramharter
- a Centre de Recherches Médicales de Lambaréné , Lambaréné , Gabon.,b Institut für Tropenmedizin , Universität Tübingen , Tübingen , Germany.,c Department of Medicine I, Division of Infectious Diseases and Tropical Medicine , Medical University of Vienna , Vienna , Austria
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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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Campo B, Vandal O, Wesche DL, Burrows JN. Killing the hypnozoite--drug discovery approaches to prevent relapse in Plasmodium vivax. Pathog Glob Health 2015; 109:107-22. [PMID: 25891812 PMCID: PMC4455353 DOI: 10.1179/2047773215y.0000000013] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The eradication of malaria will only be possible if effective, well-tolerated medicines kill hypnozoites in vivax and ovale malaria, and thus prevent relapses in patients. Despite progress in the 8-aminoquinoline series, with tafenoquine in Phase III showing clear benefits over primaquine, the drug discovery challenge to identify hypnozoiticidal or hypnozoite-activating compounds has been hampered by the dearth of biological tools and assays, which in turn has been limited by the immense scientific and logistical challenges associated with accessing relevant human tissue and sporozoites. This review summarises the existing drug discovery series and approaches concerning the goal to block relapse.
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Affiliation(s)
- Brice Campo
- Medicines for Malaria Venture, Geneva, Switzerland
| | - Omar Vandal
- The Bill and Melinda Gates Foundation, Seattle, WA, USA
| | - David L. Wesche
- The Bill and Melinda Gates Foundation, Seattle, WA, USA
- Great Lakes Drug Development/Certara, Princeton, NJ, USA
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Kumar S, Kumari R, Pandey R. New insight-guided approaches to detect, cure, prevent and eliminate malaria. PROTOPLASMA 2015; 252:717-753. [PMID: 25323622 DOI: 10.1007/s00709-014-0697-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2014] [Accepted: 09/01/2014] [Indexed: 06/04/2023]
Abstract
New challenges posed by the development of resistance against artemisinin-based combination therapies (ACTs) as well as previous first-line therapies, and the continuing absence of vaccine, have given impetus to research in all areas of malaria control. This review portrays the ongoing progress in several directions of malaria research. The variants of RTS,S and apical membrane antigen 1 (AMA1) are being developed and test adapted as multicomponent and multistage malaria control vaccines, while many other vaccine candidates and methodologies to produce antigens are under experimentation. To track and prevent the spread of artemisinin resistance from Southeast Asia to other parts of the world, rolling circle-enhanced enzyme activity detection (REEAD), a time- and cost-effective malaria diagnosis in field conditions, and a DNA marker associated with artemisinin resistance have become available. Novel mosquito repellents and mosquito trapping and killing techniques much more effective than the prevalent ones are undergoing field testing. Mosquito lines stably infected with their symbiotic wild-type or genetically engineered bacteria that kill sympatric malaria parasites are being constructed and field tested for stopping malaria transmission. A complementary approach being pursued is the addition of ivermectin-like drug molecules to ACTs to cure malaria and kill mosquitoes. Experiments are in progress to eradicate malaria mosquito by making it genetically male sterile. High-throughput screening procedures are being developed and used to discover molecules that possess long in vivo half life and are active against liver and blood stages for the fast cure of malaria symptoms caused by simple or relapsing and drug-sensitive and drug-resistant types of varied malaria parasites, can stop gametocytogenesis and sporogony and could be given in one dose. Target-based antimalarial drug designing has begun. Some of the putative next-generation antimalarials that possess in their scaffold structure several of the desired properties of malaria cure and control are exemplified by OZ439, NITD609, ELQ300 and tafenoquine that are already undergoing clinical trials, and decoquinate, usnic acid, torin-2, ferroquine, WEHI-916, MMV396749 and benzothiophene-type N-myristoyltransferase (NMT) inhibitors, which are candidates for future clinical usage. Among these, NITD609, ELQ300, decoquinate, usnic acid, torin-2 and NMT inhibitors not only cure simple malaria and are prophylactic against simple malaria, but they also cure relapsing malaria.
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Affiliation(s)
- Sushil Kumar
- SKA Institution for Research, Education and Development (SKAIRED), 4/11 SarvPriya Vihar, New Delhi, 110016, India,
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Abstract
Introduction of novel and diverse functional groups in drug discovery is always seen with hesitancy until good activity and low toxicity characteristics are proven. The introduction of fluorine in drug-like compounds is now a well-accepted strategy in medicinal chemistry. However, polyfluoroalkyl groups, with the exception of trifluoromethyl substituents, are not well explored yet. Our aim is to show to the readers how polyfluorinated groups can be beneficial to the properties of pharmaceutically active compounds by highlighting the structure–activity relationship (SAR) studies that led to the selection of polyfluorinated moieties as key structural features. Despite the fact that the use of higher polyfluoroalkyl/aryl moieties is still in its infancy, we believe that they will soon acquire the same importance of their lower parents.
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Melariri P, Kalombo L, Nkuna P, Dube A, Hayeshi R, Ogutu B, Gibhard L, deKock C, Smith P, Wiesner L, Swai H. Oral lipid-based nanoformulation of tafenoquine enhanced bioavailability and blood stage antimalarial efficacy and led to a reduction in human red blood cell loss in mice. Int J Nanomedicine 2015; 10:1493-503. [PMID: 25759576 PMCID: PMC4346002 DOI: 10.2147/ijn.s76317] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Tafenoquine (TQ), a new synthetic analog of primaquine, has relatively poor bioavailability and associated toxicity in glucose-6-phosphate dehydrogenase (G6PD)-deficient individuals. A microemulsion formulation of TQ (MTQ) with sizes <20 nm improved the solubility of TQ and enhanced the oral bioavailability from 55% to 99% in healthy mice (area under the curve 0 to infinity: 11,368±1,232 and 23,842±872 min·μmol/L) for reference TQ and MTQ, respectively. Average parasitemia in Plasmodium berghei-infected mice was four- to tenfold lower in the MTQ-treated group. In vitro antiplasmodial activities against chloroquine-sensitive and chloroquine-resistant strains of Plasmodium falciparum indicated no change in half maximal inhibitory concentration, suggesting that the microemulsion did not affect the inherent activity of TQ. In a humanized mouse model of G6PD deficiency, we observed reduction in toxicity of TQ as delivered by MTQ at low but efficacious concentrations of TQ. We hereby report an enhancement in the solubility, bioavailibility, and efficacy of TQ against blood stages of Plasmodium parasites without a corresponding increase in toxicity.
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Affiliation(s)
- Paula Melariri
- Polymers and Composites, Material Science and Manufacturing, Council for Scientific and Industrial Research, Port Elizabeth, South Africa
| | - Lonji Kalombo
- Polymer and Composites, Material Science and Manufacturing, Council for Scientific and Industrial Research, Pretoria, South Africa
| | - Patric Nkuna
- Polymer and Composites, Material Science and Manufacturing, Council for Scientific and Industrial Research, Pretoria, South Africa
| | - Admire Dube
- Polymer and Composites, Material Science and Manufacturing, Council for Scientific and Industrial Research, Pretoria, South Africa ; School of Pharmacy, University of the Western Cape, Bellville, South Africa
| | - Rose Hayeshi
- Polymer and Composites, Material Science and Manufacturing, Council for Scientific and Industrial Research, Pretoria, South Africa
| | - Benhards Ogutu
- Centre for Research in Therapeutic Sciences, Strathmore University, Nairobi, Kenya ; Centre for Clinical Research, Kenya Medical Research Institute, Nairobi, Kenya
| | - Liezl Gibhard
- Division of Pharmacology, University of Cape Town Medical School, Groote Schuur Hospital, Cape Town, South Africa
| | - Carmen deKock
- Division of Pharmacology, University of Cape Town Medical School, Groote Schuur Hospital, Cape Town, South Africa
| | - Peter Smith
- Division of Pharmacology, University of Cape Town Medical School, Groote Schuur Hospital, Cape Town, South Africa
| | - Lubbe Wiesner
- Division of Pharmacology, University of Cape Town Medical School, Groote Schuur Hospital, Cape Town, South Africa
| | - Hulda Swai
- Polymer and Composites, Material Science and Manufacturing, Council for Scientific and Industrial Research, Pretoria, South Africa
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Tekwani BL, Avula B, Sahu R, Chaurasiya ND, Khan SI, Jain S, Fasinu PS, Herath HMTB, Stanford D, Nanayakkara NPD, McChesney JD, Yates TW, ElSohly MA, Khan IA, Walker LA. Enantioselective pharmacokinetics of primaquine in healthy human volunteers. Drug Metab Dispos 2015; 43:571-7. [PMID: 25637634 DOI: 10.1124/dmd.114.061127] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Primaquine (PQ), a racemic drug, is the only treatment available for radical cure of relapsing Plasmodium vivax malaria and blocking transmission of P. falciparum malaria. Recent studies have shown differential pharmacologic and toxicologic profiles of individual PQ enantiomers in rodent, dog, and primate animal models. This study was conducted in six healthy adult human volunteers to determine the plasma pharmacokinetic profile of enantiomers of PQ and carboxyprimaquine (cPQ), the major plasma metabolite. The individuals were orally administered PQ diphosphate, equivalent to 45-mg base, 30 minutes after a normal breakfast. Blood samples were collected at different time intervals, and plasma samples were analyzed for enantiomers of PQ and cPQ. Plasma PQ concentrations were low and variable for both parent enantiomers and peaked around 2-4 hours. Peak (-)-(R)-PQ concentrations ranged from 121 ng/ml to 221 ng/ml, and peak (+)-(S)-PQ concentrations ranged from 168 ng/ml to 299 ng/ml. The cPQ concentrations were much higher and were surprisingly consistent from subject to subject. Essentially all the cPQ detected in plasma was (-)-cPQ. The peak concentrations of (-)-cPQ were observed at 8 hours (range: 1104-1756 ng/ml); however, very high concentrations were sustained through 24 hours. (+)-cPQ was two orders of magnitude lower than (-)-cPQ, and in a few subjects it was detected but only under the limit of quantification. In vitro studies with primary human hepatocytes also suggested more rapid metabolism of (-)-PQ compared with (+)-PQ. The results suggest more rapid metabolism of (-)-PQ to (-) cPQ compared with (+)-PQ. Alternatively, (+)-PQ or (+)-cPQ could be rapidly converted to another metabolite(s) or distributed to tissues. This is the first clinical report on enantioselective pharmacokinetic profiles of PQ and cPQ and supports further clinical evaluation of individual PQ enantiomers.
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Affiliation(s)
- Babu L Tekwani
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Bharathi Avula
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Rajnish Sahu
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Narayan D Chaurasiya
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Shabana I Khan
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Surendra Jain
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Pius S Fasinu
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - H M T Bandara Herath
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Donald Stanford
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - N P Dhammika Nanayakkara
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - James D McChesney
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Travis W Yates
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Mahmoud A ElSohly
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Ikhlas A Khan
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
| | - Larry A Walker
- National Center for Natural Products Research (B.L.T., B.A., R.S., N.D.C., S.I.K., S.J., P.S.F., H.M.T.B.H., D.S., N.P.D.N., M.A.E., I.A.K., L.A.W.), Departments of BioMolecular Sciences (B.L.T., S.I.K., S.J., I.A.K., L.A.W.) and Pharmaceutics (M.A.E.), School of Pharmacy, and Department of Student Health Services (T.W.Y.), University of Mississippi, University; Ironstone Separations, Inc., Etta (J.D.M.); ElSohly Laboratories, Inc., Oxford (M.A.E.), Mississippi
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Held J, Jeyaraj S, Kreidenweiss A. Antimalarial compounds in Phase II clinical development. Expert Opin Investig Drugs 2015; 24:363-82. [PMID: 25563531 DOI: 10.1517/13543784.2015.1000483] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION Malaria is a major health problem in endemic countries and chemotherapy remains the most important tool in combating it. Treatment options are limited and essentially rely on a single drug class - the artemisinins. Efforts are ongoing to restrict the evolving threat of artemisinin resistance but declining sensitivity has been reported. Fueled by the ambitious aim of malaria eradication, novel antimalarial compounds, with improved properties, are now in the progressive phase of drug development. AREAS COVERED Herein, the authors describe antimalarial compounds currently in Phase II clinical development and present the results of these investigations. EXPERT OPINION Thanks to recent efforts, a number of promising antimalarial compounds are now in the pipeline. First safety data have been generated for all of these candidates, although their efficacy as antimalarials is still unclear for most of them. Of particular note are KAE609, KAF156 and DSM265, which are of chemical scaffolds new to malaria chemotherapy and would truly diversify antimalarial options. Apart from SAR97276, which also has a novel chemical scaffold that has had its development stopped, all other compounds in the pipeline belong to already known substance classes, which have been chemically modified. At this moment in time, there is not one standout compound that will revolutionize malaria treatment but several compounds that will add to its control in the future.
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Affiliation(s)
- Jana Held
- Institut für Tropenmedizin, Eberhard Karls Universität , Wilhelmstraße 27, D-72074 Tübingen , Germany +49 7071 29 85569 ; +49 7071 295189 ;
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Zhu W, Wang J, Wang S, Gu Z, Aceña JL, Izawa K, Liu H, Soloshonok VA. Recent advances in the trifluoromethylation methodology and new CF3-containing drugs. J Fluor Chem 2014. [DOI: 10.1016/j.jfluchem.2014.06.026] [Citation(s) in RCA: 325] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Teixeira C, Vale N, Pérez B, Gomes A, Gomes JRB, Gomes P. "Recycling" classical drugs for malaria. Chem Rev 2014; 114:11164-220. [PMID: 25329927 DOI: 10.1021/cr500123g] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Cátia Teixeira
- Centro de Investigação em Química da Universidade do Porto, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , P-4169-007 Porto, Portugal.,CICECO, Departamento de Química, Universidade de Aveiro , P-3810-193 Aveiro, Portugal
| | - Nuno Vale
- Centro de Investigação em Química da Universidade do Porto, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , P-4169-007 Porto, Portugal
| | - Bianca Pérez
- Centro de Investigação em Química da Universidade do Porto, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , P-4169-007 Porto, Portugal
| | - Ana Gomes
- Centro de Investigação em Química da Universidade do Porto, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , P-4169-007 Porto, Portugal
| | - José R B Gomes
- CICECO, Departamento de Química, Universidade de Aveiro , P-3810-193 Aveiro, Portugal
| | - Paula Gomes
- Centro de Investigação em Química da Universidade do Porto, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto , P-4169-007 Porto, Portugal
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Strategic use of antimalarial drugs that block falciparum malaria parasite transmission to mosquitoes to achieve local malaria elimination. Parasitol Res 2014; 113:3535-46. [PMID: 25185662 DOI: 10.1007/s00436-014-4091-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 08/25/2014] [Indexed: 01/03/2023]
Abstract
The ultimate aim of malaria chemotherapy is not only to treat symptomatic infection but also to reduce transmission potential. With the absence of clinically proven vaccines, drug-mediated blocking of malaria transmission gains growing interest in the research agenda for malaria control and elimination. In addition to the limited arsenal of antimalarials available, the situation is further complicated by the fact that most commonly used antimalarials are being extensively resisted by the parasite and do not assist in blocking its transmission to vectors. Most antimalarials do not exhibit gametocytocidal and/ or sporontocidal activity against the sexual stages of Plasmodium falciparum but may even enhance gametocytogenesis and gametocyte transmissibility. Artemisinin derivatives and 8-aminoquinolines are useful transmission-blocking antimalarials whose optimal actions are on different stages of gametocytes. Transmission control interventions that include gametocytocides covering the spectrum of gametocyte development should be used to reduce and, if possible, stop transmission and infectivity of gametocytes to mosquitoes. Potent gametocytocidal drugs could also help deter the spread of antimalarial drug resistance. Novel proof-of-concept compounds with gametocytocidal activity, such as trioxaquines, synthetic endoperoxides, and spiroindolone, should be further tested for possible clinical utility before investigating the possibility of integrating them in transmission-reducing interventions. Strategic use of potent gametocytocides at appropriate timing with artemisinin-based combination therapies should be given attention, at least, in the short run. This review highlights the role that antimalarials could play in blocking gametocyte transmission and infectivity to mosquitoes and, hence, in reducing the potential of falciparum malaria transmissibility and drug resistance spread.
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Miller AK, Harrell E, Ye L, Baptiste-Brown S, Kleim JP, Ohrt C, Duparc S, Möhrle JJ, Webster A, Stinnett S, Hughes A, Griffith S, Beelen AP. Pharmacokinetic interactions and safety evaluations of coadministered tafenoquine and chloroquine in healthy subjects. Br J Clin Pharmacol 2014; 76:858-67. [PMID: 23701202 DOI: 10.1111/bcp.12160] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 05/09/2013] [Indexed: 11/28/2022] Open
Abstract
AIMS The long-acting 8-aminoquinoline tafenoquine (TQ) coadministered with chloroquine (CQ) may radically cure Plasmodium vivax malaria. Coadministration therapy was evaluated for a pharmacokinetic interaction and for pharmacodynamic, safety and tolerability characteristics. METHODS Healthy subjects, 18-55 years old, without documented glucose-6-phosphate dehydrogenase deficiency, received CQ alone (days 1-2, 600 mg; and day 3, 300 mg), TQ alone (days 2 and 3, 450 mg) or coadministration therapy (day 1, CQ 600 mg; day 2, CQ 600 mg + TQ 450 mg; and day 3, CQ 300 mg + TQ 450 mg) in a randomized, double-blind, parallel-group study. Blood samples for pharmacokinetic and pharmacodynamic analyses and safety data, including electrocardiograms, were collected for 56 days. RESULTS The coadministration of CQ + TQ had no effect on TQ AUC0-t , AUC0-∞ , Tmax or t1/2 . The 90% confidence intervals of CQ + TQ vs. TQ for AUC0-t , AUC0-∞ and t1/2 indicated no drug interaction. On day 2 of CQ + TQ coadministration, TQ Cmax and AUC0-24 increased by 38% (90% confidence interval 1.27, 1.64) and 24% (90% confidence interval 1.04, 1.46), respectively. The pharmacokinetics of CQ and its primary metabolite desethylchloroquine were not affected by TQ. Coadministration had no clinically significant effect on QT intervals and was well tolerated. CONCLUSIONS No clinically significant safety or pharmacokinetic/pharmacodynamic interactions were observed with coadministered CQ and TQ in healthy subjects.
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Li Q, O'Neil M, Xie L, Caridha D, Zeng Q, Zhang J, Pybus B, Hickman M, Melendez V. Assessment of the prophylactic activity and pharmacokinetic profile of oral tafenoquine compared to primaquine for inhibition of liver stage malaria infections. Malar J 2014; 13:141. [PMID: 24731238 PMCID: PMC3989846 DOI: 10.1186/1475-2875-13-141] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 04/02/2014] [Indexed: 11/10/2022] Open
Abstract
Background As anti-malarial drug resistance escalates, new safe and effective medications are necessary to prevent and treat malaria infections. The US Army is developing tafenoquine (TQ), an analogue of primaquine (PQ), which is expected to be more effective in preventing malaria in deployed military personnel. Methods To compare the prophylactic efficacy of TQ and PQ, a transgenic Plasmodium berghei parasite expressing the bioluminescent reporter protein luciferase was utilized to visualize and quantify parasite development in C57BL/6 albino mice treated with PQ and TQ in single or multiple regimens using a real-time in vivo imaging system (IVIS). As an additional endpoint, blood stage parasitaemia was monitored by flow cytometry. Comparative pharmacokinetic (PK) and liver distribution studies of oral and intravenous PQ and TQ were also performed. Results Mice treated orally with three doses of TQ at 5 mg/kg three doses of PQ at 25 mg/kg demonstrated no bioluminescence liver signal and no blood stage parasitaemia was observed suggesting both drugs showed 100% causal activity at the doses tested. Single dose oral treatment with 5 mg TQ or 25 mg of PQ, however, yielded different results as only TQ treatment resulted in causal prophylaxis in P. berghei sporozoite-infected mice. TQ is highly effective for causal prophylaxis in mice at a minimal curative single oral dose of 5 mg/kg, which is a five-fold improvement in potency versus PQ. PK studies of the two drugs administered orally to mice showed that the absolute bioavailability of oral TQ was 3.5-fold higher than PQ, and the AUC of oral TQ was 94-fold higher than oral PQ. The elimination half-life of oral TQ in mice was 28 times longer than PQ, and the liver tissue distribution of TQ revealed an AUC that was 188-fold higher than PQ. Conclusions The increased drug exposure levels and longer exposure time of oral TQ in the plasma and livers of mice highlight the lead quality attributes that explain the much improved efficacy of TQ when compared to PQ.
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Affiliation(s)
- Qigui Li
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, 503 Robert Grant Avenue, Silver Spring, MD 20910, USA.
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Gamo FJ. Antimalarial drug resistance: new treatments options for Plasmodium. DRUG DISCOVERY TODAY. TECHNOLOGIES 2014; 11:81-88. [PMID: 24847657 DOI: 10.1016/j.ddtec.2014.03.002] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Malaria is one of the world’s most deadly infectious diseases. Millions of lives are threatened by the continued development of resistance in the malaria parasite which is overcoming the effectiveness of current anti- malarial treatments. The scientific community is facing this challenge by developing new and superior therapies to combat, and potentially eradicate, this wide spread plague. New anti-Plasmodium agents derived from phe- notypic screening hits (e.g. spiroindolones) or from target based projects (e.g. DSM265) have recently entered into clinical development and hopefully will provide soon a new wave of antimalarial treatments.
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Quashie NB, Duah NO, Abuaku B, Quaye L, Ayanful-Torgby R, Akwoviah GA, Kweku M, Johnson JD, Lucchi NW, Udhayakumar V, Duplessis C, Kronmann KC, Koram KA. A SYBR Green 1-based in vitro test of susceptibility of Ghanaian Plasmodium falciparum clinical isolates to a panel of anti-malarial drugs. Malar J 2013; 12:450. [PMID: 24341604 PMCID: PMC3878558 DOI: 10.1186/1475-2875-12-450] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Accepted: 12/10/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Based on report of declining efficacy of chloroquine, Ghana shifted to the use of artemisinin-based combination therapy (ACT) in 2005 as the first-line anti-malarial drug. Since then, there has not been any major evaluation of the efficacy of anti-malarial drugs in Ghana in vitro. The sensitivity of Ghanaian Plasmodium falciparum isolates to anti-malarial drugs was, therefore, assessed and the data compared with that obtained prior to the change in the malaria treatment policy. METHODS A SYBR Green 1 fluorescent-based in vitro drug sensitivity assay was used to assess the susceptibility of clinical isolates of P. falciparum to a panel of 12 anti-malarial drugs in three distinct eco-epidemiological zones in Ghana. The isolates were obtained from children visiting health facilities in sentinel sites located in Hohoe, Navrongo and Cape Coast municipalities. The concentration of anti-malarial drug inhibiting parasite growth by 50% (IC50) for each drug was estimated using the online program, ICEstimator. RESULTS Pooled results from all the sentinel sites indicated geometric mean IC50 values of 1.60, 3.80, 4.00, 4.56, 5.20, 6.11, 10.12, 28.32, 31.56, 93.60, 107.20, and 8952.50 nM for atovaquone, artesunate, dihydroartemisin, artemether, lumefantrine, amodiaquine, mefloquine, piperaquine, chloroquine, tafenoquine, quinine, and doxycycline, respectively. With reference to the literature threshold value indicative of resistance, the parasites showed resistance to all the test drugs except the artemisinin derivatives, atovaquone and to a lesser extent, lumefantrine. There was nearly a two-fold decrease in the IC50 value determined for chloroquine in this study compared to that determined in 2004 (57.56 nM). This observation is important, since it suggests a significant improvement in the efficacy of chloroquine, probably as a direct consequence of reduced drug pressure after cessation of its use. Compared to that measured prior to the change in treatment policy, significant elevation of artesunate IC50 value was observed. The results also suggest the existence of possible cross-resistance among some of the test drugs. CONCLUSION Ghanaian P. falciparum isolates, to some extent, have become susceptible to chloroquine in vitro, however the increasing trend in artesunate IC50 value observed should be of concern. Continuous monitoring of ACT in Ghana is recommended.
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Affiliation(s)
- Neils B Quashie
- Centre for Tropical Clinical Pharmacology and Therapeutics, University of Ghana Medical School, Accra, Ghana.
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Elphinstone RE, Higgins SJ, Kain KC. Prevention of Malaria in Travelers: Bite Avoidance and Chemoprophylactic Measures. CURRENT TREATMENT OPTIONS IN INFECTIOUS DISEASES 2013. [DOI: 10.1007/s40506-013-0005-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Abstract
Malaria elimination has recently been reinstated as a global health priority but current therapies seem to be insufficient for the task. Elimination efforts require new drug classes that alleviate symptoms, prevent transmission and provide a radical cure. To develop these next-generation medicines, public-private partnerships are funding innovative approaches to identify compounds that target multiple parasite species at multiple stages of the parasite life cycle. In this Review, we discuss the cell-, chemistry- and target-based approaches used to discover new drug candidates that are currently in clinical trials or undergoing preclinical testing.
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Held J, Kreidenweiss A, Mordmüller B. Novel approaches in antimalarial drug discovery. Expert Opin Drug Discov 2013; 8:1325-37. [PMID: 24090219 DOI: 10.1517/17460441.2013.843522] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
INTRODUCTION The development of new antimalarial drugs remains of the utmost importance, since Plasmodium falciparum has developed resistance against nearly all chemotherapeutics in clinical use. In an effort to contain the resistance of P. falciparum against artemisinins and to further eradication efforts, studies are ongoing to identify novel and more efficacious approaches to develop antimalarials. AREAS COVERED The authors review the classical and new approaches to antimalarial drug discovery, with a special emphasis on the various stages of the parasite's life cycle and the different Plasmodium species. The authors discuss the methodologies and strategies for early efficacy testing that aim to narrow down the portfolio of promising compounds. EXPERT OPINION The increased efforts in the discovery and development of new antimalarial compounds have led to the recognition of new promising hits. However, there is still major roadblock of selecting the most promising compounds and then further testing them in early clinical trials, especially in the current restricted economy. Controlled human malaria infection has much potential for speeding-up the early development process of many drug candidates including those which target the pre-erythrocytic stages.
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Affiliation(s)
- Jana Held
- University of Tübingen, Institute of Tropical Medicine , Wilhelmstraße 27, D-72074 Tübingen , Germany +49 7071 29 82364 ; +49 7071 295189 ;
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Flannery EL, Fidock DA, Winzeler EA. Using genetic methods to define the targets of compounds with antimalarial activity. J Med Chem 2013; 56:7761-71. [PMID: 23927658 DOI: 10.1021/jm400325j] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Although phenotypic cellular screening has been used to drive antimalarial drug discovery in recent years, in some cases target-based drug discovery remains more attractive. This is especially true when appropriate high-throughput cellular assays are lacking, as is the case for drug discovery efforts that aim to provide a replacement for primaquine (4-N-(6-methoxyquinolin-8-yl)pentane-1,4-diamine), the only drug that can block Plasmodium transmission to Anopheles mosquitoes and eliminate liver-stage hypnozoites. At present, however, there are no known chemically validated parasite protein targets that are important in all Plasmodium parasite developmental stages and that can be used in traditional biochemical compound screens. We propose that a plethora of novel, chemically validated, cross-stage antimalarial targets still remain to be discovered from the ~5,500 proteins encoded by the Plasmodium genomes. Here we discuss how in vitro evolution of drug-resistant strains of Plasmodium falciparum and subsequent whole-genome analysis can be used to find the targets of some of the many compounds discovered in whole-cell phenotypic screens.
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Affiliation(s)
- Erika L Flannery
- Department of Pediatrics, University of California, San Diego, School of Medicine , 9500 Gilman Drive 0741, La Jolla, California 92093, United States
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Howes RE, Battle KE, Satyagraha AW, Baird JK, Hay SI. G6PD deficiency: global distribution, genetic variants and primaquine therapy. ADVANCES IN PARASITOLOGY 2013; 81:133-201. [PMID: 23384623 DOI: 10.1016/b978-0-12-407826-0.00004-7] [Citation(s) in RCA: 155] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Glucose-6-phosphate dehydrogenase (G6PD) is a potentially pathogenic inherited enzyme abnormality and, similar to other human red blood cell polymorphisms, is particularly prevalent in historically malaria endemic countries. The spatial extent of Plasmodium vivax malaria overlaps widely with that of G6PD deficiency; unfortunately the only drug licensed for the radical cure and relapse prevention of P. vivax, primaquine, can trigger severe haemolytic anaemia in G6PD deficient individuals. This chapter reviews the past and current data on this unique pharmacogenetic association, which is becoming increasingly important as several nations now consider strategies to eliminate malaria transmission rather than control its clinical burden. G6PD deficiency is a highly variable disorder, in terms of spatial heterogeneity in prevalence and molecular variants, as well as its interactions with P. vivax and primaquine. Consideration of factors including aspects of basic physiology, diagnosis, and clinical triggers of primaquine-induced haemolysis is required to assess the risks and benefits of applying primaquine in various geographic and demographic settings. Given that haemolytically toxic antirelapse drugs will likely be the only therapeutic options for the coming decade, it is clear that we need to understand in depth G6PD deficiency and primaquine-induced haemolysis to determine safe and effective therapeutic strategies to overcome this hurdle and achieve malaria elimination.
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von Seidlein L, Auburn S, Espino F, Shanks D, Cheng Q, McCarthy J, Baird K, Moyes C, Howes R, Ménard D, Bancone G, Winasti-Satyahraha A, Vestergaard LS, Green J, Domingo G, Yeung S, Price R. Review of key knowledge gaps in glucose-6-phosphate dehydrogenase deficiency detection with regard to the safe clinical deployment of 8-aminoquinoline treatment regimens: a workshop report. Malar J 2013; 12:112. [PMID: 23537118 PMCID: PMC3616837 DOI: 10.1186/1475-2875-12-112] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Accepted: 03/14/2013] [Indexed: 01/24/2023] Open
Abstract
The diagnosis and management of glucose-6-phosphate dehydrogenase (G6PD) deficiency is a crucial aspect in the current phases of malaria control and elimination, which will require the wider use of 8-aminoquinolines for both reducing Plasmodium falciparum transmission and achieving the radical cure of Plasmodium vivax. 8-aminoquinolines, such as primaquine, can induce severe haemolysis in G6PD-deficient individuals, potentially creating significant morbidity and undermining confidence in 8-aminoquinoline prescription. On the other hand, erring on the side of safety and excluding large numbers of people with unconfirmed G6PD deficiency from treatment with 8-aminoquinolines will diminish the impact of these drugs. Estimating the remaining G6PD enzyme activity is the most direct, accessible, and reliable assessment of the phenotype and remains the gold standard for the diagnosis of patients who could be harmed by the administration of primaquine. Genotyping seems an unambiguous technique, but its use is limited by cost and the large range of recognized G6PD genotypes. A number of enzyme activity assays diagnose G6PD deficiency, but they require a cold chain, specialized equipment, and laboratory skills. These assays are impractical for care delivery where most patients with malaria live. Improvements to the diagnosis of G6PD deficiency are required for the broader and safer use of 8-aminoquinolines to kill hypnozoites, while lower doses of primaquine may be safely used to kill gametocytes without testing. The discussions and conclusions of a workshop conducted in Incheon, Korea in May 2012 to review key knowledge gaps in G6PD deficiency are reported here.
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Affiliation(s)
- Lorenz von Seidlein
- Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia.
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41
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Douglas NM, John GK, von Seidlein L, Anstey NM, Price RN. Chemotherapeutic strategies for reducing transmission of Plasmodium vivax malaria. ADVANCES IN PARASITOLOGY 2013. [PMID: 23199490 DOI: 10.1016/b978-0-12-397900-1.00005-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Effective use of anti-malarial drugs is key to reducing the transmission potential of Plasmodium vivax. In patients presenting with symptomatic disease, treatment with potent and relatively slowly eliminated blood schizontocidal regimens administered concurrently with a supervised course of 7 mg/kg primaquine over 7-14 days has potential to exert the greatest transmission-blocking benefit. Given the spread of chloroquine-resistant P. vivax strains, the artemisinin combination therapies dihydroartemisinin + piperaquine and artesunate + mefloquine are currently the most assured means of preventing P. vivax recrudescence. Preliminary evidence suggests that, like chloroquine, these combinations potentiate the hypnozoitocidal effect of primaquine, but further supportive evidence is required. In view of the high rate of P. vivax relapse following falciparum infections in co-endemic regions, there is a strong argument for broadening current radical cure policy to include the administration of hypnozoitocidal doses of primaquine to patients with Plasmodium falciparum malaria. The most important reservoir for P. vivax transmission is likely to be very low-density, asymptomatic infections, the majority of which will arise from liver-stage relapses. Therefore, judicious mass administration of hypnozoitocidal therapy will reduce transmission of P. vivax to a greater extent than strategies focused on treatment of symptomatic patients. An efficacious hypnozoitocidal agent with a short curative treatment course would be particularly useful in mass drug administration campaigns.
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Affiliation(s)
- Nicholas M Douglas
- Centre for Tropical Medicine, Nuffield Department of Clinical Medicine, University of Oxford, Oxford, UK.
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42
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Baird JK. Tropical Health and Sustainability. Infect Dis (Lond) 2013. [DOI: 10.1007/978-1-4614-5719-0_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
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Castelli F, Tomasoni LR, Matteelli A. Advances in the treatment of malaria. Mediterr J Hematol Infect Dis 2012; 4:e2012064. [PMID: 23170193 PMCID: PMC3499999 DOI: 10.4084/mjhid.2012.064] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Accepted: 09/24/2012] [Indexed: 12/25/2022] Open
Abstract
Malaria still claims a heavy toll of deaths and disabilities even at the beginning of the third millennium. The inappropriate sequential use of drug monotherapy in the past has facilitated the spread of drug-resistant P. falciparum, and to a lesser extend P. vivax, strains in most of the malaria endemic areas, rendering most anti-malarial ineffective. In the last decade, a new combination strategy based on artemisinin derivatives (ACT) has become the standard of treatment for most P. falciparum malaria infections. This strategy could prevent the selection of resistant strains by rapidly decreasing the parasitic burden (by the artemisinin derivative, mostly artesunate) and exposing the residual parasite to effective concentrations of the partner drug. The widespread use of this strategy is somehow constrained by cost and by the inappropriate use of artemisinin, with possible impact on resistance, as already sporadically observed in South East Asia. Parenteral artesunate has now become the standard of care for severe malaria, even if quinine still retains its value in case artesunate is not immediately available. The appropriateness of pre-referral use of suppository artesunate is under close monitoring, while waiting for an effective anti-malarial vaccine to be made available.
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Affiliation(s)
- Francesco Castelli
- Chair of Infectious Diseases, University of Brescia, Italy
- University Division of Infectious and Tropical Diseases, University of Brescia and Spedali Civili General Hospital, Brescia (Italy)
| | - Lina Rachele Tomasoni
- University Division of Infectious and Tropical Diseases, University of Brescia and Spedali Civili General Hospital, Brescia (Italy)
| | - Alberto Matteelli
- University Division of Infectious and Tropical Diseases, University of Brescia and Spedali Civili General Hospital, Brescia (Italy)
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44
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Abstract
Malaria chemotherapy is under constant threat from the emergence and spread of multidrug resistance of Plasmodium falciparum. Resistance has been observed to almost all currently used antimalarials. Some drugs are also limited by toxicity. A fundamental component of the strategy for malaria chemotherapy is based on prompt, effective and safe antimalarial drugs. To counter the threat of resistance of P. falciparum to existing monotherapeutic regimens, current malaria treatment is based principally on the artemisinin group of compounds, either as monotherapy or artemisinin-based combination therapies for treatment of both uncomplicated and severe falciparum malaria. Key advantages of artemisinins over the conventional antimalarials include their rapid and potent action, with good tolerability profiles. Their action also covers transmissible gametocytes, resulting in decreased disease transmission. Up to now there has been no prominent report of drug resistance to this group of compounds. Treatment of malaria in pregnant women requires special attention in light of limited treatment options caused by potential teratogenicity coupled with a paucity of safety data for the mother and fetus. Treatment of other malaria species is less problematic and chloroquine is still the drug of choice, although resistance of P. vivax to chloroquine has been reported. Multiple approaches to the identification of new antimalarial targets and promising antimalarial drugs are being pursued in order to cope with drug resistance.
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Affiliation(s)
- Kesara Na-Bangchang
- Faculty of Allied Health Sciences, Thammasat University (Rangsit Campus), Paholyothin Road, Klong Luang District, Pathumtanee 12121, Thailand.
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Carmona-Fonseca J. Recurrencias de malaria por Plasmodium vivax según el uso de primaquina: análisis de estudios descriptivos longitudinales. REVISTA BRASILEIRA DE EPIDEMIOLOGIA 2012; 15:488-503. [DOI: 10.1590/s1415-790x2012000300005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 02/10/2012] [Indexed: 11/21/2022] Open
Abstract
ANTECEDENTES: la primaquina (PQ) es el único medicamento disponible en el mercado para prevenir recurrencias del paludismo por Plasmodium vivax pero varios aspectos suyos se desconocen. OBJETIVO: comparar regímenes de PQ para prevenir recurrencias de malaria vivax. METODOLOGÍA: revisión sistemática de datos. RESULTADOS: 1. ¿Según los estudios descriptivos, la PQ es eficaz para prevenir las recurrencias del paludismo vivax? Sí. La comparación de estudios que no usaron PQ con otros que sí la aplicaron, en cualquier esquema, mostró que si no se usa PQ la recurrencia es altamente probable. 2. ¿Tienen la misma eficacia dosis diarias (mg/kg) iguales pero dosis totales diferentes? La dosis total de 75 mg es tanto o más eficaz que la de 210 mg. 3. ¿La eficacia anti-recurrencias depende del lugar donde sucede la infección? Si. Hay variación según país y región. 4. ¿La frecuencia de recurrencias depende del tiempo de seguimiento post tratamiento? La respuesta no es uniforme para todos los lugares. CONCLUSIONES: la PQ resultó eficaz para prevenir las recurrencias, pero no fue 100%. Las dosis totales de 210 y de 75 mg tuvieron igual eficacia, pero 75 mg sólo han sido evaluados en India, donde P. vivax parece ser más sensible a la PQ que en otros lugares. Parece indudable la influencia del lugar en la proporción de recurrencias, incluso con una misma dosis total. El papel del tiempo de seguimiento no resultó claro. Deben evaluarse esquemas alternativos al estándar, que tiene eficacia promedio de 90% o más.
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Baird JK. Primaquine toxicity forestalls effective therapeutic management of the endemic malarias. Int J Parasitol 2012; 42:1049-54. [PMID: 22968164 DOI: 10.1016/j.ijpara.2012.06.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Revised: 06/01/2012] [Accepted: 06/16/2012] [Indexed: 10/28/2022]
Abstract
Treatment of acutely ill patients, informed by a diagnosis of the species of Plasmodium involved, has long dominated strategic thinking in malaria chemotherapeutics. This bias for both acute illness and access to diagnosis resulted in therapeutic strategies poorly suited to malaria as it occurs in endemic zones. Most of those malarias do not provoke illness and occur beyond diagnostic reach for technical or practical reasons. Therapies effective against all species and stages would likely prove more practical in endemic zones, especially if safely administered without laboratory screening for contraindications. The primary impediment to such therapies is the mild to severe hemolytic toxicity of primaquine in patients with glucose-6-phosphate dehydrogenase deficiency. Primaquine is the only treatment licensed for therapy against relapse caused by dormant liver stages occurring in some species, and against the sexual blood stages responsible for transmission to mosquitoes in all species. Despite being licensed over 50 years ago, no alternative drugs have been developed, and safer dosing regimens of primaquine have not been explored. These failures forestalled the emergence of therapies practical for use in endemic zones, especially in the context of eliminating transmission.
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Affiliation(s)
- J Kevin Baird
- Eijkman-Oxford Clinical Research Unit, Jakarta, Indonesia.
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Buchholz K, Burke TA, Williamson KC, Wiegand RC, Wirth DF, Marti M. A high-throughput screen targeting malaria transmission stages opens new avenues for drug development. J Infect Dis 2011; 203:1445-53. [PMID: 21502082 PMCID: PMC3080890 DOI: 10.1093/infdis/jir037] [Citation(s) in RCA: 88] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A major goal of the worldwide malaria eradication program is the reduction and eventual elimination of malaria transmission. All currently available antimalarial compounds were discovered on the basis of their activity against the asexually reproducing red blood cell stages of the parasite, which are responsible for the morbidity and mortality of human malaria. Resistance against these compounds is widespread, and there is an urgent need for novel approaches to reduce the emergence of resistance to new antimalarials as they are introduced. We have established and validated the first high-throughput assay targeting the red blood cell parasite stage required for transmission, the sexually reproducing gametocyte. This assay will permit identification of compounds specifically targeting the transmission stages in addition to the asexual stage parasites. Such stage-specific compounds may be used in a combination therapy, reducing the emergence of resistance by blocking transmission of resistant parasites that may be selected in a patient.
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Affiliation(s)
- Kathrin Buchholz
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, MA 02115, USA
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Grimberg BT, Mehlotra RK. Expanding the Antimalarial Drug Arsenal-Now, But How? Pharmaceuticals (Basel) 2011; 4:681-712. [PMID: 21625331 PMCID: PMC3102560 DOI: 10.3390/ph4050681] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2011] [Revised: 04/09/2011] [Accepted: 04/19/2011] [Indexed: 01/24/2023] Open
Abstract
The number of available and effective antimalarial drugs is quickly dwindling. This is mainly because a number of drug resistance-associated mutations in malaria parasite genes, such as crt, mdr1, dhfr/dhps, and others, have led to widespread resistance to all known classes of antimalarial compounds. Unfortunately, malaria parasites have started to exhibit some level of resistance in Southeast Asia even to the most recently introduced class of drugs, artemisinins. While there is much need, the antimalarial drug development pipeline remains woefully thin, with little chemical diversity, and there is currently no alternative to the precious artemisinins. It is difficult to predict where the next generation of antimalarial drugs will come from; however, there are six major approaches: (i) re-optimizing the use of existing antimalarials by either replacement/rotation or combination approach; (ii) repurposing drugs that are currently used to treat other infections or diseases; (iii) chemically modifying existing antimalarial compounds; (iv) exploring natural sources; (v) large-scale screening of diverse chemical libraries; and (vi) through parasite genome-based ("targeted") discoveries. When any newly discovered effective antimalarial treatment is used by the populus, we must maintain constant vigilance for both parasite-specific and human-related factors that are likely to hamper its success. This article is neither comprehensive nor conclusive. Our purpose is to provide an overview of antimalarial drug resistance, associated parasite genetic factors (1. Introduction; 2. Emergence of artemisinin resistance in P. falciparum), and the antimalarial drug development pipeline (3. Overview of the global pipeline of antimalarial drugs), and highlight some examples of the aforementioned approaches to future antimalarial treatment. These approaches can be categorized into "short term" (4. Feasible options for now) and "long term" (5. Next generation of antimalarial treatment-Approaches and candidates). However, these two categories are interrelated, and the approaches in both should be implemented in parallel with focus on developing a successful, long-lasting antimalarial chemotherapy.
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Affiliation(s)
- Brian T. Grimberg
- Center for Global Health and Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA; E-Mails: (B.T.G.); (R.K.M.); Tel.: +1-216-368-6328 or +1-216-368-6172, Fax: +1-216-368-4825
| | - Rajeev K. Mehlotra
- Center for Global Health and Diseases, School of Medicine, Case Western Reserve University, Cleveland, OH 44106, USA; E-Mails: (B.T.G.); (R.K.M.); Tel.: +1-216-368-6328 or +1-216-368-6172, Fax: +1-216-368-4825
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49
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Blocking Plasmodium falciparum Malaria Transmission with Drugs: The Gametocytocidal and Sporontocidal Properties of Current and Prospective Antimalarials. Pharmaceuticals (Basel) 2010. [PMCID: PMC4052541 DOI: 10.3390/ph4010044] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Drugs that kill or inhibit the sexual stages of Plasmodium could potentially amplify or synergize the impact of other interventions by blocking transmission to mosquitoes. Primaquine and other 8-aminoquinolines have long offered such potential, but safety and other concerns have limited their use. Although transmission-blocking properties are not often a priority of drug discovery efforts, a number of interesting gametocytocidal and/or sporontocidal drug candidates have emerged in recent years. Some still bear significant technical and safety concerns, while others have passed clinical trials and are on the verge of entering the antimalarial armamentarium. Recent advances in our knowledge of gametocyte differentiation, gametogenesis and sporogony have also led to the identification of a large array of potential new targets for drugs that might interfere with malaria transmission. This review examines the properties of existing and prospective drugs, mechanisms of action, counter-indications and their potential role in regional malaria elimination efforts.
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50
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Abstract
The flow of international travellers to and from malaria-endemic areas, especially Africa, has increased in recent years. Apart from the very high morbidity and mortality burden imposed on malaria-endemic areas, imported malaria is the main cause of fever possibly causing severe disease and death in travellers coming from tropical and subtropical areas, particularly Sub-Saharan Africa. The importance of behavioural preventive measures (bed nets, repellents, etc.), adequate chemoprophylaxis and, in selected circumstances, stand-by emergency treatment may not be overemphasized. However, no prophylactic regimen may offer complete protection. Expert advice is needed to tailor prophylactic advice according to traveller (age, baseline clinical conditions, etc.) and travel (destination, season, etc.) characteristics in order to reduce malaria risk.
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