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Chamboko CR, Veldman W, Tata RB, Schoeberl B, Tastan Bishop Ö. Human Cytochrome P450 1, 2, 3 Families as Pharmacogenes with Emphases on Their Antimalarial and Antituberculosis Drugs and Prevalent African Alleles. Int J Mol Sci 2023; 24:ijms24043383. [PMID: 36834793 PMCID: PMC9961538 DOI: 10.3390/ijms24043383] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 01/30/2023] [Accepted: 02/06/2023] [Indexed: 02/10/2023] Open
Abstract
Precision medicine gives individuals tailored medical treatment, with the genotype determining the therapeutic strategy, the appropriate dosage, and the likelihood of benefit or toxicity. Cytochrome P450 (CYP) enzyme families 1, 2, and 3 play a pivotal role in eliminating most drugs. Factors that affect CYP function and expression have a major impact on treatment outcomes. Therefore, polymorphisms of these enzymes result in alleles with diverse enzymatic activity and drug metabolism phenotypes. Africa has the highest CYP genetic diversity and also the highest burden of malaria and tuberculosis, and this review presents current general information on CYP enzymes together with variation data concerning antimalarial and antituberculosis drugs, while focusing on the first three CYP families. Afrocentric alleles such as CYP2A6*17, CYP2A6*23, CYP2A6*25, CYP2A6*28, CYP2B6*6, CYP2B6*18, CYP2C8*2, CYP2C9*5, CYP2C9*8, CYP2C9*9, CYP2C19*9, CYP2C19*13, CYP2C19*15, CYP2D6*2, CYP2D6*17, CYP2D6*29, and CYP3A4*15 are implicated in diverse metabolic phenotypes of different antimalarials such as artesunate, mefloquine, quinine, primaquine, and chloroquine. Moreover, CYP3A4, CYP1A1, CYP2C8, CYP2C18, CYP2C19, CYP2J2, and CYP1B1 are implicated in the metabolism of some second-line antituberculosis drugs such as bedaquiline and linezolid. Drug-drug interactions, induction/inhibition, and enzyme polymorphisms that influence the metabolism of antituberculosis, antimalarial, and other drugs, are explored. Moreover, a mapping of Afrocentric missense mutations to CYP structures and a documentation of their known effects provided structural insights, as understanding the mechanism of action of these enzymes and how the different alleles influence enzyme function is invaluable to the advancement of precision medicine.
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Affiliation(s)
- Chiratidzo R Chamboko
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, Makhanda 6139, South Africa
| | - Wayde Veldman
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, Makhanda 6139, South Africa
| | - Rolland Bantar Tata
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, Makhanda 6139, South Africa
| | - Birgit Schoeberl
- Translational Medicine, Novartis Institutes for BioMedical Research, 220 Massachusetts Ave, Cambridge, MA 02139, USA
| | - Özlem Tastan Bishop
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, Makhanda 6139, South Africa
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Tsamesidis I, Mousavizadeh F, Egwu CO, Amanatidou D, Pantaleo A, Benoit-Vical F, Reybier K, Giannis A. In Vitro and In Silico Antimalarial Evaluation of FM-AZ, a New Artemisinin Derivative. MEDICINES (BASEL, SWITZERLAND) 2022; 9:8. [PMID: 35200752 PMCID: PMC8880451 DOI: 10.3390/medicines9020008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 01/17/2022] [Accepted: 01/17/2022] [Indexed: 11/16/2022]
Abstract
Artemisinin-based Combination Therapies (ACTs) are currently the frontline treatment against Plasmodium falciparum malaria, but parasite resistance to artemisinin (ART) and its derivatives, core components of ACTs, is spreading in the Mekong countries. In this study, we report the synthesis of several novel artemisinin derivatives and evaluate their in vitro and in silico capacity to counteract Plasmodium falciparum artemisinin resistance. Furthermore, recognizing that the malaria parasite devotes considerable resources to minimizing the oxidative stress that it creates during its rapid consumption of hemoglobin and the release of heme, we sought to explore whether further augmentation of this oxidative toxicity might constitute an important addition to artemisinins. The present report demonstrates, in vitro, that FM-AZ, a newly synthesized artemisinin derivative, has a lower IC50 than artemisinin in P. falciparum and a rapid action in killing the parasites. The docking studies for important parasite protein targets, PfATP6 and PfHDP, complemented the in vitro results, explaining the superior IC50 values of FM-AZ in comparison with ART obtained for the ART-resistant strain. However, cross-resistance between FM-AZ and artemisinins was evidenced in vitro.
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Affiliation(s)
- Ioannis Tsamesidis
- UMR 152 Pharma-Dev, Universite de Toulouse III, IRD, UPS, 31400 Toulouse, France; (C.O.E.); (K.R.)
- Department of Biomedical Sciences, School of Health, International Hellenic University, 57400 Thessaloniki, Greece;
| | - Farnoush Mousavizadeh
- Institute for Organic Chemistry, University of Leipzig, Johannisallee 29, 04301 Leipzig, Germany;
| | - Chinedu O. Egwu
- UMR 152 Pharma-Dev, Universite de Toulouse III, IRD, UPS, 31400 Toulouse, France; (C.O.E.); (K.R.)
- Medical Biochemistry, College of Medicine, Alex-Ekwueme Federal University, Ndufu-Alike Ikwo, P.M.B. 1010, Abakaliki 482131, Nigeria
- Laboratoire de Chimie de Coordination, LCC—CNRS, Universite de Toulouse, 31077 Toulouse, France;
| | - Dionysia Amanatidou
- Department of Biomedical Sciences, School of Health, International Hellenic University, 57400 Thessaloniki, Greece;
| | - Antonella Pantaleo
- Department of Biomedical Sciences, University of Sassari, 07100 Sassari, Italy;
| | - Françoise Benoit-Vical
- Laboratoire de Chimie de Coordination, LCC—CNRS, Universite de Toulouse, 31077 Toulouse, France;
| | - Karine Reybier
- UMR 152 Pharma-Dev, Universite de Toulouse III, IRD, UPS, 31400 Toulouse, France; (C.O.E.); (K.R.)
| | - Athanassios Giannis
- Institute for Organic Chemistry, University of Leipzig, Johannisallee 29, 04301 Leipzig, Germany;
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Predicting the Disposition of the Antimalarial Drug Artesunate and Its Active Metabolite Dihydroartemisinin Using Physiologically Based Pharmacokinetic Modeling. Antimicrob Agents Chemother 2021; 65:AAC.02280-20. [PMID: 33361307 DOI: 10.1128/aac.02280-20] [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: 10/27/2020] [Accepted: 12/14/2020] [Indexed: 01/03/2023] Open
Abstract
Artemisinin-based combination therapies (ACTs) have proven to be effective in helping to combat the global malaria epidemic. To optimally apply these drugs, information about their tissue-specific disposition is required, and one approach to predict these pharmacokinetic characteristics is physiologically based pharmacokinetic (PBPK) modeling. In this study, a whole-body PBPK model was developed to simulate the time-dependent tissue concentrations of artesunate (AS) and its active metabolite, dihydroartemisinin (DHA). The model was developed for both rats and humans and incorporated drug metabolism of the parent compound and major metabolite. Model calibration was conducted using data from the literature in a Bayesian framework, and model verification was assessed using separate sets of data. Results showed good agreement between model predictions and the validation data, demonstrating the capability of the model in predicting the blood, plasma, and tissue pharmacokinetics of AS and DHA. It is expected that such a tool will be useful in characterizing the disposition of these chemicals and ultimately improve dosing regimens by enabling a quantitative assessment of the tissue-specific drug levels critical in the evaluation of efficacy and toxicity.
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Cancer combination therapies with artemisinin-type drugs. Biochem Pharmacol 2017; 139:56-70. [DOI: 10.1016/j.bcp.2017.03.019] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 03/28/2017] [Indexed: 01/28/2023]
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Li Q, Xie LH, Si Y, Wong E, Upadhyay R, Yanez D, Weina PJ. Toxicokinetics and Hydrolysis of Artelinate and Artesunate in Malaria-Infected Rats. Int J Toxicol 2016; 24:241-50. [PMID: 16126618 DOI: 10.1080/10915810591007201] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Comparative toxicokinetic (TK) and hydrolysis studies of intravenously administered two new antimalarial agents, artelinate (AL) and artesunate (AS), were performed in malaria-infected rats using three daily equimolar doses (96 μmoles/kg). The TK evaluation was related to select one drug for severe malaria treatment in U.S. Army. Drug concentration of AS with daily dose of 36.7 mg/kg was one-third less on day 3 than on day 1, which resembled its active metabolite, dihydroartemisinin (DHA), suggesting an autoinduction of hepatic drug-metabolizing enzymes for AS. The results were similar to other artemisinin drugs, but not for AL. TK parameters of AL were very comparable from day 1 to day 3 at same AS molecular dose at 40.6 mg/kg. AS is the prodrug of DHA with the DHA/AS ratio of 5.26 compared to the ratio of 0.01 for DHA/AL. Other TK parameters revealed that the total AUC1–3 days (84.4 μg · h ml−1) of AL was fivefold higher than that of AS (15.7 mu;g h ml−1 of AS plus DHA). The elimination half-life of AL (7.1 h) was much longer than that of AS (0.36 h) or DHA (0.72 h). The remarkable alteration of the TK shape of AL may be caused by poor conversion rates to DHA and an enterohepatic circulation, which is confirmed by the present TK and tissue distribution studies. Compared to AS, higher drug exposure levels and longer exposure time of AL in the rat blood may be the cause of its increased toxicity.
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Affiliation(s)
- Qigui Li
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20910-7500, USA.
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Xie LH, Johnson TO, Weina PJ, Si Y, Haeberle A, Upadhyay R, Wong E, Li Q. Risk Assessment and Therapeutic Indices of Artesunate and Artelinate in Plasmodium berghei–Infected and Uninfected Rats. Int J Toxicol 2016; 24:251-64. [PMID: 16126619 DOI: 10.1080/10915810591007229] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Artesunate (AS) is being developed as a potential agent for the treatment of severe and complicated malaria. A risk assessment of the therapeutic index and related hematological changes of AS and artelinate (AL) following daily intravenous injection for 3 days was conducted in Plasmodium berghei–infected and uninfected rats. The minimum doses of AS and AL for parasitemia suppression were 2.3 and 2.5 mg/kg, respectively, and the suppressive doses for half parasitemia (SD50) were 7.4 and 8.6 mg/kg, respectively. The maximum tolerated dose (MTD) for AS was 240 mg/kg with a therapeutic index of 32.6. The MTD for AL was 80 mg/kg with a therapeutic index of 9.3. Hematological changes were studied on days 1 and 8 after the final dosing. In both AS- and AL-treated rats, dose-dependent and rapidly reversible hematological changes (significant reductions in RBC, HCT, Hb, and reticulocyte levels) were seen in the peripheral blood. Bone marrow evaluation revealed a statistically significant reduction in the myeloid/erythroid ratio only at the highest dose of AS (240 mg/kg), albeit still within the normal ratio range (1.0–1.5:1.0). Looking at the respective therapeutic indices the authors have concluded that AS is much safer than AL. Both drugs induced hematological changes in rats that parallel the dose-dependent, reversible anemia and reticulocytopenia previously reported in animals and humans. However, no significant bone marrow depression was seen for either agent.
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Affiliation(s)
- Lisa H Xie
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, Maryland 20307-5100, USA
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Comparative pharmacokinetics and pharmacodynamics of intravenous artelinate versus artesunate in uncomplicated Plasmodium coatneyi-infected rhesus monkey model. Malar J 2016; 15:453. [PMID: 27599723 PMCID: PMC5011932 DOI: 10.1186/s12936-016-1456-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Accepted: 07/28/2016] [Indexed: 11/25/2022] Open
Abstract
Background The US Army designed artelinate/lysine salt (AL) to overcome the instability of sodium artesunate in aqueous solution (AS). To select the most efficacious artemisinin treatment, direct comparison was performed in an uncomplicated non-human primate malaria model. Methods Splenectomized rhesus monkeys were inoculated with Plasmodium coatneyi and on day six, single equimolar loading dose of IV AL (11.8 mg kg−1) or IV AS (8 mg kg−1) were administered followed by 1/2 the first dose once daily for 2 more days. Blood smear were performed twice daily and the number of parasites were counted microscopically. Blood samples were obtained after the first dose within 6 h for pharmacokinetic (PK) and ex vivo pharmacodynamic evaluation by simultaneously measuring plasma drug concentration and anti-malarial activity against Plasmodium falciparum in vitro. Results The anti-P. coatneyi in vivo activity of both compounds were comparable, but the ex vivo anti-P. falciparum potency of the IV AS regimen as administered was sevenfold higher than that of IV AL. Comparing in vivo pharmacodynamics of AL and AS, daily assessed parasite counts showed comparable 99 % parasite clearance times (PC99: 2.03, 1.84 day), parasite clearance rates (5.34, 4.13 per min) and clearance half-life (PCt1/2: 7.79, 10.1 h). This study showed strong and significant inverse correlation between PCt1/2 and t1/2 of AS + DHA, and AUC0–∞ of DHA, and correlated with Vz of AS (r2 > 0.7, p ≤ 0.002). Lastly, following IV AL, there was a modest inverse correlation between PCt1/2 and Cmax (r2 0.6, p ≤ 0.04). Although all tested monkeys recrudesced subsequently, two died following AL regimen before parasite clearance. While the aetiology of those deaths could not be definitively determined, pathologic evidence favoured a sepsis-like syndrome and suggested that severe malaria was more likely than drug toxicity. Conclusion The model demonstrated that both AS and DHA contributed to the anti-malarial activity of IV AS, while IV AL activity was largely restricted to the parent drug. Parasite clearance was strongly and linearly dependent on drug exposure for both artemisinin regimens. However, IV AS had higher ex vivo potency against P. falciparum, leading to an IND filing for GMP manufactured AS in the United States. Electronic supplementary material The online version of this article (doi:10.1186/s12936-016-1456-6) contains supplementary material, which is available to authorized users.
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Backman JT, Filppula AM, Niemi M, Neuvonen PJ. Role of Cytochrome P450 2C8 in Drug Metabolism and Interactions. Pharmacol Rev 2016; 68:168-241. [PMID: 26721703 DOI: 10.1124/pr.115.011411] [Citation(s) in RCA: 150] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
During the last 10-15 years, cytochrome P450 (CYP) 2C8 has emerged as an important drug-metabolizing enzyme. CYP2C8 is highly expressed in human liver and is known to metabolize more than 100 drugs. CYP2C8 substrate drugs include amodiaquine, cerivastatin, dasabuvir, enzalutamide, imatinib, loperamide, montelukast, paclitaxel, pioglitazone, repaglinide, and rosiglitazone, and the number is increasing. Similarly, many drugs have been identified as CYP2C8 inhibitors or inducers. In vivo, already a small dose of gemfibrozil, i.e., 10% of its therapeutic dose, is a strong, irreversible inhibitor of CYP2C8. Interestingly, recent findings indicate that the acyl-β-glucuronides of gemfibrozil and clopidogrel cause metabolism-dependent inactivation of CYP2C8, leading to a strong potential for drug interactions. Also several other glucuronide metabolites interact with CYP2C8 as substrates or inhibitors, suggesting that an interplay between CYP2C8 and glucuronides is common. Lack of fully selective and safe probe substrates, inhibitors, and inducers challenges execution and interpretation of drug-drug interaction studies in humans. Apart from drug-drug interactions, some CYP2C8 genetic variants are associated with altered CYP2C8 activity and exhibit significant interethnic frequency differences. Herein, we review the current knowledge on substrates, inhibitors, inducers, and pharmacogenetics of CYP2C8, as well as its role in clinically relevant drug interactions. In addition, implications for selection of CYP2C8 marker and perpetrator drugs to investigate CYP2C8-mediated drug metabolism and interactions in preclinical and clinical studies are discussed.
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Affiliation(s)
- Janne T Backman
- Department of Clinical Pharmacology, University of Helsinki (J.T.B., A.M.F., M.N., P.J.N.), and Helsinki University Hospital, Helsinki, Finland (J.T.B., M.N., P.J.N.)
| | - Anne M Filppula
- Department of Clinical Pharmacology, University of Helsinki (J.T.B., A.M.F., M.N., P.J.N.), and Helsinki University Hospital, Helsinki, Finland (J.T.B., M.N., P.J.N.)
| | - Mikko Niemi
- Department of Clinical Pharmacology, University of Helsinki (J.T.B., A.M.F., M.N., P.J.N.), and Helsinki University Hospital, Helsinki, Finland (J.T.B., M.N., P.J.N.)
| | - Pertti J Neuvonen
- Department of Clinical Pharmacology, University of Helsinki (J.T.B., A.M.F., M.N., P.J.N.), and Helsinki University Hospital, Helsinki, Finland (J.T.B., M.N., P.J.N.)
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Tripathi CB, Beg S, Kaur R, Shukla G, Bandopadhyay S, Singh B. Systematic development of optimized SNEDDS of artemether with improved biopharmaceutical and antimalarial potential. Drug Deliv 2016; 23:3209-3223. [DOI: 10.3109/10717544.2016.1162876] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Chandra Bhushan Tripathi
- UGC Centre of Advanced Studies, University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh, India,
| | - Sarwar Beg
- UGC Centre of Advanced Studies, University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh, India,
| | - Ripandeep Kaur
- UGC- Centre of Excellence in Applications of Nanomaterials, Nanoparticles and Nanocomposites (Biomedical Sciences), Panjab University, Chandigarh, India,
| | - Geeta Shukla
- Department of Microbiology, Panjab University, Chandigarh, India, and
| | - Shantanu Bandopadhyay
- Division of Pharmaceutics, PDM College of Pharmacy, Sarai Aurangabad, Bahadurgarh, Haryana, India
| | - Bhupinder Singh
- UGC Centre of Advanced Studies, University Institute of Pharmaceutical Sciences, Panjab University, Chandigarh, India,
- UGC- Centre of Excellence in Applications of Nanomaterials, Nanoparticles and Nanocomposites (Biomedical Sciences), Panjab University, Chandigarh, India,
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Tilley L, Charman SA, Vennerstrom JL. Semisynthetic Artemisinin and Synthetic Peroxide Antimalarials. NEGLECTED DISEASES AND DRUG DISCOVERY 2011. [DOI: 10.1039/9781849733496-00033] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Since the discovery of the endoperoxide sesquiterpene lactone artemisinin, numerous second-generation semisynthetic artemisinins and synthetic peroxides have been prepared and tested for their antimalarial properties. Using a case-study approach, we describe the discovery of the investigational semisynthetic artemisinins artelinic acid (8) and artemisone (9), and the structurally diverse synthetic peroxides arteflene (10), fenozan B07 (11), arterolane (12), PA1103/SAR116242 (13), and RKA182 (14).
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Affiliation(s)
- Leann Tilley
- Department of Biochemistry and Centre of Excellence for Coherent X-rayScience, La Trobe University Melbourne, Victoria 3086 Australia
| | - Susan A. Charman
- Centre for Drug Candidate Optimisation, Monash Institute of Pharmaceutical Sciences Monash University (Parkville Campus), 381 Royal Parade, Parkville, Victoria 3052 Australia
| | - Jonathan L. Vennerstrom
- College of Pharmacy University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha NE USA
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Greenblatt DJ, Venkatakrishnan K, Harmatz JS, Parent SJ, von Moltke LL. Sources of variability in ketoconazole inhibition of human cytochrome P450 3Ain vitro. Xenobiotica 2010; 40:713-20. [DOI: 10.3109/00498254.2010.506224] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Niwa T, Murayama N, Yamazaki H. Comparison of the Contributions of Cytochromes P450 3A4 and 3A5 in Drug Oxidation Rates and Substrate Inhibition. ACTA ACUST UNITED AC 2010. [DOI: 10.1248/jhs.56.239] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Toshiro Niwa
- Laboratory of Drug Metabolism and Pharmacokinetics, Showa Pharmaceutical University
| | - Norie Murayama
- Laboratory of Drug Metabolism and Pharmacokinetics, Showa Pharmaceutical University
| | - Hiroshi Yamazaki
- Laboratory of Drug Metabolism and Pharmacokinetics, Showa Pharmaceutical University
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Zhou SF, Zhou ZW, Huang M. Polymorphisms of human cytochrome P450 2C9 and the functional relevance. Toxicology 2009; 278:165-88. [PMID: 19715737 DOI: 10.1016/j.tox.2009.08.013] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 08/18/2009] [Accepted: 08/21/2009] [Indexed: 12/19/2022]
Abstract
Human cytochrome P450 2C9 (CYP2C9) accounts for ∼20% of hepatic total CYP content and metabolizes ~15% clinical drugs such as phenytoin, S-warfarin, tolbutamide, losartan, and many nonsteroidal anti-inflammatory agents (NSAIDs). CYP2C9 is highly polymorphic, with at least 33 variants of CYP2C9 (*1B through *34) being identified so far. CYP2C9*2 is frequent among Caucasians with ~1% of the population being homozygous carriers and 22% are heterozygous. The corresponding figures for the CYP2C9*3 allele are 0.4% and 15%, respectively. There are a number of clinical studies addressing the impact of CYP2C9 polymorphisms on the clearance and/or therapeutic response of therapeutic drugs. These studies have highlighted the importance of the CYP2C9*2 and *3 alleles as a determining factor for drug clearance and drug response. The CYP2C9 polymorphisms are relevant for the efficacy and adverse effects of numerous NSAIDs, sulfonylurea antidiabetic drugs and, most critically, oral anticoagulants belonging to the class of vitamin K epoxide reductase inhibitors. Warfarin has served as a practical example of how pharmacogenetics can be utilized to achieve maximum efficacy and minimum toxicity. For many of these drugs, a clear gene-dose and gene-effect relationship has been observed in patients. In this regard, CYP2C9 alleles can be considered as a useful biomarker in monitoring drug response and adverse effects. Genetic testing of CYP2C9 is expected to play a role in predicting drug clearance and conducting individualized pharmacotherapy. However, prospective clinical studies with large samples are warranted to establish gene-dose and gene-effect relationships for CYP2C9 and its substrate drugs.
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Affiliation(s)
- Shu-Feng Zhou
- School of Health Sciences, RMIT University, Victoria 3083, Australia.
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Mehlotra RK, Henry-Halldin CN, Zimmerman PA. Application of pharmacogenomics to malaria: a holistic approach for successful chemotherapy. Pharmacogenomics 2009; 10:435-49. [PMID: 19290792 DOI: 10.2217/14622416.10.3.435] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Drug resistance in malaria jeopardizes the most elementary objectives of malaria control--reducing suffering and eliminating mortality. An important, and so far the only known, mechanism of drug resistance appears to be polymorphisms in the malaria parasite genes. Efforts to circumvent antimalarial drug resistance now range from the use of combination therapies with existing agents to genomics-based studies directed toward discovering novel targets and agents. However, the potential contribution of host genetic/molecular factors, particularly those associated with antimalarial drug metabolism, remains largely unexplored. Our knowledge concerning the basic mechanisms involved in the pharmacokinetics of antimalarial drugs is fragmentary. In addition, the link between antimalarial drug pharmacokinetics and treatment outcomes is generally unclear. The purpose of this article is to provide general background information on antimalarial drug resistance and associated parasite genetic factors, and subsequently highlight the aforementioned unexplored and unclear areas, with a view to stimulate much needed further research.
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Affiliation(s)
- Rajeev K Mehlotra
- Center for Global Health and Diseases, Case Western Reserve University, School of Medicine, Wolstein Research Building #4204, 2103 Cornell Road, Cleveland, OH 44106-7286, USA.
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Li Q, Xie LH, Johnson TO, Si Y, Haeberle AS, Weina PJ. Toxicity evaluation of artesunate and artelinate in Plasmodium berghei-infected and uninfected rats. Trans R Soc Trop Med Hyg 2007; 101:104-12. [PMID: 16860356 DOI: 10.1016/j.trstmh.2006.04.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2005] [Revised: 04/07/2006] [Accepted: 04/07/2006] [Indexed: 11/15/2022] Open
Abstract
A recent therapeutic index study in rats demonstrated that i.v. artesunate (AS) is safer than artelinate (AL). The present study of acute toxicity illustrated an LD(50) of 177 mg/kg and 488 mg/kg for AL and AS, respectively, following daily i.v. injection for 3 days in Plasmodium berghei-infected rats. In uninfected rats, the LD(50) values were 116 mg/kg and 351 mg/kg after a single dose of AL and AS, respectively. This study showed vascular necrosis in 50% of the animals at 13.5 mg/kg AL and at 42.8 mg/kg AS. Animals also showed moderate signs of renal failure at 40 mg/kg AL and 240 mg/kg AS (100 times higher than the therapeutic dose). Histopathological evaluation demonstrated mild to moderate tubular necrosis in uninfected rats treated with 40 mg/kg AL and 240 mg/kg AS; interestingly, fewer pathological lesions were observed in malaria-infected rats. Renal injury was reversible in all cases by Day 8 after cessation of dosing. No neurotoxicity was seen in any case with all i.v. regimens. In conclusion, AL and AS exhibit less toxic effects in P. berghei-infected rats than in uninfected rats. Both agents caused irreversible vascular irritation, reversible nephrotoxicity and no neurotoxicity at high doses. The data indicate that AS is three times safer than AL in rats.
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Affiliation(s)
- Qigui Li
- Division of Experimental Therapeutics, Walter Reed Army Institute of Research, Silver Spring, MD 20307-5100, USA.
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16
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Abstract
Artesunate, a semi-synthetic derivative of a naturally occurring anti-malarial artemisinin was compared with chloroquine in C57BL/6 mice infected with Plasmodium berghei Anka (PbA). A 7-day oral administration of artesunate prevented parasitaemia at 10 mg/kg/day. However, recrudescence of parasitaemia and cerebral malaria occurred upon cessation of treatment followed by death within 28 days. However, a 14-day course of artesunate (100 mg/kg/day) prevented completely the development of parasitaemia and cerebral malaria with a survival of more than 60-days as did 10 mg/kg/day chloroquine. These data demonstrate that oral artesunate inhibits PbA and prevents cerebral malaria, but needs to be administered at high dose and for prolonged time to eradicate PbA infection in mice.
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Wienkers LC. Factors confounding the successful extrapolation of in vitro CYP3A inhibition information to the in vivo condition. Eur J Pharm Sci 2002; 15:239-42. [PMID: 11923055 DOI: 10.1016/s0928-0987(02)00002-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
For the most part, the majority of adverse drug-drug interactions, which are pharmacokinetic in origin, can be understood in terms of alterations of cytochrome P450-catalyzed reactions. Much is known about the human P450 enzymes, and in many cases it is possible to apply this information to clinically related issues. Of the relatively small subset of the total number of human P450s, CYP3A4 appears to be responsible for the largest fraction of the drug oxidation reactions. As a consequence many important drug-drug interactions observed in the clinic are associated with drugs which are principally metabolized by CYP3A4. The two major reasons for drug-drug interactions involving CYP3A4 are induction and inhibition, with inhibition appearing to be the more important in terms of known clinical problems. Fortunately, with the available knowledge of human P450s and in vitro reagents, it is possible to do experiments with drugs to predict the in vivo condition. The goal of these studies is not only to improve predictions about which drugs might show serious P450 interaction problems, but also to decrease the number of in vivo interaction studies that must be performed in drug development. The focus of the current report is to describe some of the confounding factors associated with in vitro drug inhibition studies and the impact of these issues on in vitro/in vivo extrapolations.
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Affiliation(s)
- Larry C Wienkers
- Global Drug Metabolism, Pharmacia, 301 Henrietta St., Kalamazoo, MI 49009, USA.
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Abstract
This chapter is an update of the data on substrates, reactions, inducers, and inhibitors of human CYP enzymes published previously by Rendic and DiCarlo (1), now covering selection of the literature through 2001 in the reference section. The data are presented in a tabular form (Table 1) to provide a framework for predicting and interpreting the new P450 metabolic data. The data are formatted in an Excel format as most suitable for off-line searching and management of the Web-database. The data are presented as stated by the author(s) and in the case when several references are cited the data are presented according to the latest published information. The searchable database is available either as an Excel file (for information contact the author), or as a Web-searchable database (Human P450 Metabolism Database, www.gentest.com) enabling the readers easy and quick approach to the latest updates on human CYP metabolic reactions.
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Affiliation(s)
- Slobodan Rendic
- Faculty of Pharmacy and Biochemistry, University of Zagreb, Croatia.
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Avery MA, Alvim-Gaston M, Rodrigues CR, Barreiro EJ, Cohen FE, Sabnis YA, Woolfrey JR. Structure-activity relationships of the antimalarial agent artemisinin. 6. The development of predictive in vitro potency models using CoMFA and HQSAR methodologies. J Med Chem 2002; 45:292-303. [PMID: 11784134 DOI: 10.1021/jm0100234] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Artemisinin (1) is a unique sesquiterpene peroxide occurring as a constituent of Artemisia annua L. Because of the effectiveness of Artemisinin in the treatment of drug-resistant Plasmodium falciparum and its rapid clearance of cerebral malaria, development of clinically useful semisynthetic drugs for severe and complicated malaria (artemether, artesunate) was prompt. However, recent reports of fatal neurotoxicity in animals with dihydroartemisinin derivatives such as artemether have spawned a renewed effort to develop nontoxic analogues of artemisinin. In our effort to develop more potent, less neurotoxic agents for the oral treatment of drug-resistant malaria, we utilized comparative molecular field analysis (CoMFA) and hologram QSAR (HQSAR), beginning with a series of 211 artemisinin analogues with known in vitro antimalarial activity. CoMFA models were based on two conformational hypotheses: (a) that the X-ray structure of artemisinin represents the bioactive shape of the molecule or (b) that the hemin-docked conformation is the bioactive form of the drug. In addition, we examined the effect of inclusion or exclusion of racemates in the partial least squares (pls) analysis. Databases derived from the original 211 were split into chiral (n = 157), achiral (n = 34), and mixed databases (n = 191) after leaving out a test set of 20 compounds. HQSAR and CoMFA models were compared in terms of their potential to generate robust QSAR models. The r(2) and q(2) (cross-validated r(2)) were used to assess the statistical quality of our models. Another statistical parameter, the ratio of the standard error to the activity range (s/AR), was also generated. CoMFA and HQSAR models were developed having statistically excellent properties, which also possessed good predictive ability for test set compounds. The best model was obtained when racemates were excluded from QSAR analysis. Thus, CoMFA of the n = 157 database gave excellent predictions with outstanding statistical properties. HQSAR did an outstanding job in statistical analysis and also handled predictions well.
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Affiliation(s)
- Mitchell A Avery
- Department of Medicinal Chemistry, School of Pharmacy, Thad Cochran National Center for Natural Products Research, University of Mississippi, University, Mississippi 38677, USA.
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Suputtamongkol Y, Newton PN, Angus B, Teja-Isavadharm P, Keeratithakul D, Rasameesoraj M, Pukrittayakamee S, White NJ. A comparison of oral artesunate and artemether antimalarial bioactivities in acute falciparum malaria. Br J Clin Pharmacol 2001; 52:655-61. [PMID: 11736876 PMCID: PMC2014567 DOI: 10.1046/j.1365-2125.2001.01458.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2000] [Accepted: 06/14/2001] [Indexed: 11/20/2022] Open
Abstract
AIMS Artesunate and artemether are the two most widely used artemisinin derivatives in the treatment of uncomplicated Plasmodium falciparum malaria, but there is little information on their comparative pharmacokinetics. The aim of this study was to examine the relative oral antimalarial bioavailability and pharmacokinetics of the two derivatives. METHODS The pharmacokinetic properties of oral artesunate and artemether (4 mg kg(-1)) were compared in a randomized cross-over study of 14 adult patients in western Thailand with acute uncomplicated Plasmodium falciparum malaria. Antimalarial activity was compared using a previously validated, sensitive bioassay. RESULTS Despite a 29% lower molar dose, oral artesunate administration resulted in significantly larger mean area under the plasma antimalarial activity time curve and median maximum plasma antimalarial activity than after oral artemether (P CONCLUSIONS The oral antimalarial bioavailability following artemether was significantly lower than that after artesunate. Artemether oral antimalarial bioavailability is reduced in acute malaria.
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Navaratnam V, Mansor SM, Sit NW, Grace J, Li Q, Olliaro P. Pharmacokinetics of artemisinin-type compounds. Clin Pharmacokinet 2000; 39:255-70. [PMID: 11069212 DOI: 10.2165/00003088-200039040-00002] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Various compounds of the artemisinin family are currently used for the treatment of patients with malaria worldwide. They are characterised by a short half-life and feature the most rapidly acting antimalarial drugs to date. They are increasingly being used, often in combination with other drugs, although our knowledge of their main pharmacological features (including their absorption, distribution, metabolism and excretion) is still incomplete. Such data are particularly important in the case of combinations. Artemisinin derivatives are converted primarily, but to different extents, to the bioactive metabolite artenimol after either parenteral or gastrointestinal administration. The rate of conversion is lowest for artelinic acid (designed to protect the molecule against metabolism) and highest for the water-soluble artesunate. The absolute and relative bioavailability of these compounds has been established in animals, but not in humans, with the exception of artesunate. Oral bioavailability in animals ranges, approximately, between 19 and 35%. A first-pass effect is highly probably for all compounds when administered orally. Artemisinin compounds bind selectively to malaria-infected erythrocytes to yet unidentified targets. They also bind modestly to human plasma proteins, ranging from 43% for artenimol to 81.5% for artelinic acid. Their mode of action is still not completely understood, although different theories have been proposed. The lipid-soluble artemether and artemotil are released slowly when administered intramuscularly because of the 'depot' effect related to the oil formulation. Understanding the pharmacokinetic profile of these 2 drugs helps us to explain the characteristics of the toxicity and neurotoxicity. The water-soluble artesunate is rapidly converted to artenimol at rates that vary with the route of administration, but the processes need to be characterised further, including the relative contribution of pH and enzymes in tissues, blood and liver. This paper intends to summarise contemporary knowledge of the pharmacokinetics of this class of compounds and highlight areas that need further research.
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Affiliation(s)
- V Navaratnam
- Centre for Drug Research, University Sains Malaysia, Penang
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Newton P, Suputtamongkol Y, Teja-Isavadharm P, Pukrittayakamee S, Navaratnam V, Bates I, White N. Antimalarial bioavailability and disposition of artesunate in acute falciparum malaria. Antimicrob Agents Chemother 2000; 44:972-7. [PMID: 10722499 PMCID: PMC89800 DOI: 10.1128/aac.44.4.972-977.2000] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The pharmacokinetic properties of oral and intravenous artesunate (2 mg/kg of body weight) were studied in 19 adult patients with acute uncomplicated Plasmodium falciparum malaria by using a randomized crossover design. A sensitive bioassay was used to measure the antimalarial activity in plasma which results from artesunate and its principal metabolite, dihydroartemisinin. The oral study was repeated with 15 patients during convalescence. The mean absolute oral bioavailability of the antimalarial agent in patients with acute malaria was 61% (95% confidence interval [CI], 52 to 70%). The absorption and elimination of oral artesunate were rapid, with a mean elimination half-life of antimalarial activity of 43 min (95% CI, 33 to 53 min). Following oral administration to patients with acute falciparum malaria, peak antimalarial activity in plasma and the area under the plasma concentration-time curve were approximately double those during convalescence and the apparent volume of distribution and clearance were approximately half those during convalescence (P < or = 0.005). Acute malaria is associated with a significant reduction in the clearance of artesunate-associated antimalarial activity.
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Affiliation(s)
- P Newton
- Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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