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Nevirapine Biotransformation Insights: An Integrated In Vitro Approach Unveils the Biocompetence and Glutathiolomic Profile of a Human Hepatocyte-Like Cell 3D Model. Int J Mol Sci 2020; 21:ijms21113998. [PMID: 32503263 PMCID: PMC7312429 DOI: 10.3390/ijms21113998] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 05/20/2020] [Accepted: 05/29/2020] [Indexed: 02/06/2023] Open
Abstract
The need for competent in vitro liver models for toxicological assessment persists. The differentiation of stem cells into hepatocyte-like cells (HLC) has been adopted due to its human origin and availability. Our aim was to study the usefulness of an in vitro 3D model of mesenchymal stem cell-derived HLCs. 3D spheroids (3D-HLC) or monolayer (2D-HLC) cultures of HLCs were treated with the hepatotoxic drug nevirapine (NVP) for 3 and 10 days followed by analyses of Phase I and II metabolites, biotransformation enzymes and drug transporters involved in NVP disposition. To ascertain the toxic effects of NVP and its major metabolites, the changes in the glutathione net flux were also investigated. Phase I enzymes were induced in both systems yielding all known correspondent NVP metabolites. However, 3D-HLCs showed higher biocompetence in producing Phase II NVP metabolites and upregulating Phase II enzymes and MRP7. Accordingly, NVP-exposure led to decreased glutathione availability and alterations in the intracellular dynamics disfavoring free reduced glutathione and glutathionylated protein pools. Overall, these results demonstrate the adequacy of the 3D-HLC model for studying the bioactivation/metabolism of NVP representing a further step to unveil toxicity mechanisms associated with glutathione net flux changes.
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Bienczak A, Denti P, Cook A, Wiesner L, Mulenga V, Kityo C, Kekitiinwa A, Gibb DM, Burger D, Walker AS, McIlleron H. Determinants of virological outcome and adverse events in African children treated with paediatric nevirapine fixed-dose-combination tablets. AIDS 2017; 31:905-915. [PMID: 28060017 PMCID: PMC5572624 DOI: 10.1097/qad.0000000000001376] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
BACKGROUND Nevirapine is the only nonnucleoside reverse transcriptase inhibitor currently available as a paediatric fixed-dose-combination tablet and is widely used in African children. Nonetheless, the number of investigations into pharmacokinetic determinants of virological suppression in African children is limited, and the predictive power of the current therapeutic range was never evaluated in this population, thereby limiting treatment optimization. METHODS We analysed data from 322 African children (aged 0.3-13 years) treated with nevirapine, lamivudine, and either abacavir, stavudine, or zidovudine, and followed up to 144 weeks. Nevirapine trough concentration (Cmin) and other factors were tested for associations with viral load more than 100 copies/ml and transaminase increases more than grade 1 using proportional hazard and logistic models in 219 initially antiretroviral treatment (ART)-naive children. RESULTS Pre-ART viral load, adherence, and nevirapine Cmin were associated with viral load nonsuppression [hazard ratio = 2.08 (95% confidence interval (CI): 1.50-2.90, P < 0.001) for 10-fold higher pre-ART viral load, hazard ratio = 0.78 (95% CI: 0.68-0.90, P < 0.001) for 10% improvement in adherence, and hazard ratio = 0.94 (95% CI: 0.90-0.99, P = 0.014) for a 1 mg/l increase in nevirapine Cmin]. There were additional effects of pre-ART CD4 cell percentage and clinical site. The risk of virological nonsuppression decreased with increasing nevirapine Cmin, and there was no clear Cmin threshold predictive of virological nonsuppression. Transient transaminase elevations more than grade 1 were associated with high Cmin (>12.4 mg/l), hazard ratio = 5.18 (95% CI 1.95-13.80, P < 0.001). CONCLUSION Treatment initiation at lower pre-ART viral load and higher pre-ART CD4 cell percentage, increased adherence, and maintaining average Cmin higher than current target could improve virological suppression of African children treated with nevirapine without increasing toxicity.
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Affiliation(s)
- Andrzej Bienczak
- aDivision of Clinical Pharmacology, Department of Medicine, University of Cape Town, Cape Town, South Africa bMRC Clinical Trials Unit at University College London, London, United Kingdom cDepartment of Paediatrics and Child Health, University Teaching Hospital, Lusaka, Zambia dJoint Clinical Research Centre eBaylor College of Medicine Bristol Myers Squibb Children's Clinical Centre of Excellence, Kampala, Uganda fGulu Regional Centre of Excellence, Gulu, Uganda gDepartment of Pharmacy, Radboud University Medical Centre, Nijmegen, The Netherlands. *Ann S. Walker and Helen McIlleron contributed equally to the article
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Abstract
Drug-induced hepatotoxicity (DIH) is a significant cause of acute liver failure and liver transplantation. Diagnosis is challenging due to the idiosyncratic nature, its presentation in the form of other liver disease, and the lack of a definite diagnostic criteria. Generation of reactive metabolites, oxidative stress, and mitochondrial dysfunction are common mechanisms involved in DIH. Certain risk factors associated with a drug and within an individual further predispose patients to DIH.
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Affiliation(s)
- Amina Ibrahim Shehu
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, 3rd Floor Salk Pavillion, Pittsburgh, PA 15261, USA
| | - Xiaochao Ma
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, 3rd Floor Salk Pavillion, Pittsburgh, PA 15261, USA
| | - Raman Venkataramanan
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, 718 Salk Hall, 3501 Terrace Street, Pittsburgh, PA 15261, USA.
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Arab-Alameddine M, Décosterd LA, Buclin T, Telenti A, Csajka C. Antiretroviral drug toxicity in relation to pharmacokinetics, metabolic profile and pharmacogenetics. Expert Opin Drug Metab Toxicol 2016; 7:609-22. [PMID: 21500966 DOI: 10.1517/17425255.2011.562891] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Besides therapeutic effectiveness, drug tolerability is a key issue for treatments that must be taken indefinitely. Given the high prevalence of toxicity in HIV therapy, the factors implicated in drug-induced morbidities should be identified in order to improve the safety, tolerability and adherence to the treatments. Current approaches have focused almost exclusively on parent drug concentrations; whereas recent evidence suggests that drug metabolites resulting from complex genetic and environmental influences can also contribute to treatment outcome. Pharmacogenetic variations have shown to play a relevant role in the variability observed in antiretroviral drug exposure, clinical response and sometimes toxicity. The integration of pharmacokinetic, pharmacogenetic and metabolic determinants will more probably address current therapeutic needs in patients. AREAS COVERED This review offers a concise description of three classes of antiretroviral drugs. The review looks at the metabolic profile of these drugs and gives a comprehensive summary of the existing literature on the influence of pharmacogenetics on their pharmacokinetics and metabolic pathways, and the associated drug or metabolite toxicity. EXPERT OPINION Due to the high prevalence of toxicity and the related risk of low adherence to the treatments, association of kinetic, genetic and metabolic markers predictive of therapeutic or toxicity outcomes could represent a more complete approach for optimizing antiretroviral therapy.
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Affiliation(s)
- Mona Arab-Alameddine
- Department of Clinical Pharmacology and Toxicology, University Hospital and University of Lausanne, Beaumont, Lausanne, Switzerland
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Mak A, Uetrecht J. The Combination of Anti-CTLA-4 and PD1-/- Mice Unmasks the Potential of Isoniazid and Nevirapine To Cause Liver Injury. Chem Res Toxicol 2015; 28:2287-91. [PMID: 26529122 DOI: 10.1021/acs.chemrestox.5b00305] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Our laboratory recently reported what we believe is the first valid animal model of idiosyncratic drug-induced liver injury (IDILI) by treating PD1-/- mice with an anti-CTLA-4 antibody and amodiaquine (AQ). PD1 and CTLA-4 are important immune checkpoint receptors that are involved in inducing immune tolerance. This model was able to produce significant liver injury that looks very similar to the liver injury seen in humans. Although this model was shown to work with AQ, the question becomes whether blocking immune tolerance would unmask the potential of other drugs to cause IDILI. In this study, we tested isoniazid and nevirapine, both drugs with significant histories of causing IDILI in humans even though they do not cause significant injury in animals with doses that result in therapeutic blood levels. Both drugs in combination with these immune checkpoint inhibitors caused mild but significant delayed onset liver injury, which is similar to the mild injury that they can cause in humans. INH-induced liver injury in this model was associated with an increase in NK cells, while NVP-induced liver injury was associated with a greater increase in CD8 T cells. Although the liver injury caused by these drugs in this model was mild, these results suggest that impairing immune tolerance may be a general method for unmasking the potential of drugs to cause IDILI and therefore provide a screening tool for drug development.
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Affiliation(s)
- Alastair Mak
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto , Toronto, Ontario M5S 3M2, Canada
| | - Jack Uetrecht
- Department of Pharmaceutical Sciences, Faculty of Pharmacy, University of Toronto , Toronto, Ontario M5S 3M2, Canada
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Marinho AT, Rodrigues PM, Caixas U, Antunes AMM, Branco T, Harjivan SG, Marques MM, Monteiro EC, Pereira SA. Differences in nevirapine biotransformation as a factor for its sex-dependent dimorphic profile of adverse drug reactions. J Antimicrob Chemother 2013; 69:476-82. [PMID: 24051761 DOI: 10.1093/jac/dkt359] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
OBJECTIVES Nevirapine is widely used for the treatment of HIV-1 infection; however, its chronic use has been associated with severe liver and skin toxicity. Women are at increased risk for these toxic events, but the reasons for the sex-related differences are unclear. Disparities in the biotransformation of nevirapine and the generation of toxic metabolites between men and women might be the underlying cause. The present work aimed to explore sex differences in nevirapine biotransformation as a potential factor in nevirapine-induced toxicity. METHODS All included subjects were adults who had been receiving 400 mg of nevirapine once daily for at least 1 month. Blood samples were collected and the levels of nevirapine and its phase I metabolites were quantified by HPLC. Anthropometric and clinical data, and nevirapine metabolite profiles, were assessed for sex-related differences. RESULTS A total of 52 patients were included (63% were men). Body weight was lower in women (P = 0.028) and female sex was associated with higher alkaline phosphatase (P = 0.036) and lactate dehydrogenase (P = 0.037) levels. The plasma concentrations of nevirapine (P = 0.030) and the metabolite 3-hydroxy-nevirapine (P = 0.035), as well as the proportions of the metabolites 12-hydroxy-nevirapine (P = 0.037) and 3-hydroxy-nevirapine (P = 0.001), were higher in women, when adjusted for body weight. CONCLUSIONS There was a sex-dependent variation in nevirapine biotransformation, particularly in the generation of the 12-hydroxy-nevirapine and 3-hydroxy-nevirapine metabolites. These data are consistent with the sex-dependent formation of toxic reactive metabolites, which may contribute to the sex-dependent dimorphic profile of nevirapine toxicity.
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Affiliation(s)
- Aline T Marinho
- Centro de Estudos de Doenças Crónicas (CEDOC), NOVA Medical School, Universidade Nova de Lisboa, Campo dos Mártires da Pátria, 130, 1169-056 Lisboa, Portugal
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Pharmacokinetics of phase I nevirapine metabolites following a single dose and at steady state. Antimicrob Agents Chemother 2013; 57:2154-60. [PMID: 23459477 DOI: 10.1128/aac.02294-12] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Nevirapine is one of the most extensively prescribed antiretrovirals worldwide. The present analyses used data and specimens from two prior studies to characterize and compare plasma nevirapine phase I metabolite profiles following a single 200-mg oral dose of nevirapine in 10 HIV-negative African Americans and a steady-state 200-mg twice-daily dose in 10 HIV-infected Cambodians. Nevirapine was assayed by high-performance liquid chromatography (HPLC). The 2-, 3-, 8- and 12-hydroxy and 4-carboxy metabolites of nevirapine were assayed by liquid chromatography-tandem mass spectrometry (LC/MS/MS). Pharmacokinetic parameters were calculated by noncompartmental analysis. The metabolic index for each metabolite was defined as the ratio of the metabolite area under the concentration-time curve (AUC) to the nevirapine AUC. Every metabolite concentration was much less than the corresponding nevirapine concentration. The predominant metabolite after single dose and at steady state was 12-hydroxynevirapine. From single dose to steady state, the metabolic index increased for 3-hydroxynevirapine (P < 0.01) but decreased for 2-hydroxynevirapine (P < 0.001). The 3-hydroxynevirapine metabolic index was correlated with nevirapine apparent clearance (P < 0.001). These findings are consistent with induction of CYP2B6 (3-hydroxy metabolite) and a possible inhibition of CYP3A (2-hydroxy metabolite), although these are preliminary data. There were no such changes in metabolic indexes for 12-hydroxynevirapine or 4-carboxynevirapine. Two subjects with the CYP2B6 *6*6 genetic polymorphism had metabolic indexes in the same range as other subjects. These results suggest that nevirapine metabolite profiles change over time under the influence of enzyme induction, enzyme inhibition, and host genetics. Further work is warranted to elucidate nevirapine biotransformation pathways and implications for drug efficacy and toxicity.
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Sharma AM, Li Y, Novalen M, Hayes MA, Uetrecht J. Bioactivation of nevirapine to a reactive quinone methide: implications for liver injury. Chem Res Toxicol 2012; 25:1708-19. [PMID: 22793666 PMCID: PMC3475366 DOI: 10.1021/tx300172s] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2012] [Indexed: 01/11/2023]
Abstract
Nevirapine (NVP) treatment is associated with a significant incidence of liver injury. We developed an anti-NVP antiserum to determine the presence and pattern of covalent binding of NVP to mouse, rat, and human hepatic tissues. Covalent binding to hepatic microsomes from male C57BL/6 mice and male Brown Norway rats was detected on Western blots; the major protein had a mass of ~55 kDa. Incubation of NVP with rat CYP3A1 and 2C11 or human CYP3A4 also led to covalent binding. Treatment of female Brown Norway rats or C57BL/6 mice with NVP led to extensive covalent binding to a wide range of proteins. Co-treatment with 1-aminobenzotriazole dramatically changed the pattern of binding. The covalent binding of 12-hydroxy-NVP, the pathway that leads to a skin rash, was much less than that of NVP, both in vitro and in vivo. An analogue of NVP in which the methyl hydrogens were replaced by deuterium also produced less covalent binding than NVP. These data provide strong evidence that covalent binding of NVP in the liver is due to a quinone methide formed by oxidation of the methyl group. Attempts were made to develop an animal model of NVP-induced liver injury in mice. There was a small increase in ALT in some NVP-treated male C57BL/6 mice at 3 weeks that resolved despite continued treatment. Male Cbl-b(-/-) mice dosed with NVP had an increase in ALT of >200 U/L, which also resolved despite continued treatment. Liver histology in these animals showed focal areas of complete necrosis, while most of the liver appeared normal. This is a different pattern from the histology of NVP-induced liver injury in humans. This is the first study to report hepatic covalent binding of NVP and also liver injury in mice. It is likely that the quinone methide metabolite is responsible for NVP-induced liver injury.
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Affiliation(s)
- Amy M. Sharma
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada M5S
3M2
| | - Yan Li
- Therapure
Biopharma Inc., 2585 Meadowpine Boulevard, Mississauga,
Ontario, L5N 8H9
| | - Maria Novalen
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada M5S
3M2
| | - M. Anthony Hayes
- Department
of Pathobiology, Ontario Veterinary College, University
of Guelph, Ontario N1G 2W1, Canada
| | - Jack Uetrecht
- Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada M5S
3M2
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Nevirapine pharmacokinetics and risk of rash and hepatitis among HIV-infected sub-Saharan African women. AIDS 2012; 26:833-41. [PMID: 22301417 DOI: 10.1097/qad.0b013e328351a521] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
OBJECTIVES To estimate nevirapine (NVP) pharmacokinetics and examine its association with rash and/or hepatotoxicity in women starting antiretroviral treatment in the AIDS Clinical Trials Group A5208/OCTANE study in Africa. DESIGN In HIV-infected, nonpregnant women with screening CD4 cell count less than 200 cells/μl randomized to NVP (twice daily, after 14-day once-daily lead-in period) and tenofovir/emtricitabine, single NVP blood samples were collected 14 and 28 days following randomization. Rash and hepatotoxicity that occurred during therapy, or within 7 days after the last dose of NVP, were defined as toxicity. METHODS NVP pharmacokinetics were modeled by population pharmacokinetic analysis. Individual Bayesian pharmacokinetic estimates were used to calculate clearance, 24-h area under the curve, and predicted plasma concentrations. RESULTS Median week 4 NVP clearance was 2 l/h. Among the 359 women, 194 (54%) developed a rash of any grade; 82 (23%) had grade 2+ and nine (3%) had grade 3+ rash. Median clearance was 1.7 l/h for participants exhibiting 3+ rash versus 2 l/h in women without 3+ rash (P = 0.046). The odds of developing 3+ rash was 50% higher for every 20% decrease in clearance (P = 0.046). NVP discontinuation due to rash/liver toxicity was significantly more common among women with pretreatment CD4 cell count more than 250 cells/μl (P = 0.003). CONCLUSION In this study, HIV-infected African women starting a NVP-based antiretroviral regimen had a lower NVP clearance compared to previous reports. Severe rash, but not hepatotoxicity, was associated with higher NVP exposure. Albeit observed in a small number of women, baseline CD4 cell count at least 250 cells/μl was significantly associated with NVP toxicity.
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Ng W, Lobach AR, Zhu X, Chen X, Liu F, Metushi IG, Sharma A, Li J, Cai P, Ip J, Novalen M, Popovic M, Zhang X, Tanino T, Nakagawa T, Li Y, Uetrecht J. Animal Models of Idiosyncratic Drug Reactions. CURRENT CONCEPTS IN DRUG METABOLISM AND TOXICOLOGY 2012; 63:81-135. [DOI: 10.1016/b978-0-12-398339-8.00003-3] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Roth RA, Ganey PE. Animal models of idiosyncratic drug-induced liver injury—Current status. Crit Rev Toxicol 2011; 41:723-39. [DOI: 10.3109/10408444.2011.575765] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Muret P, Piedoux S, Solas C, Quaranta S. Niveau de preuve du suivi therapeutique pharmacologique de la névirapine. Therapie 2011; 66:187-95. [DOI: 10.2515/therapie/2011030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Accepted: 04/19/2011] [Indexed: 11/20/2022]
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Mahungu TW, Smith CJ, Turner F, Egan D, Youle M, Johnson MA, Khoo S, Back DJ, Owen A. Cytochrome P450 2B6 516G→T is associated with plasma concentrations of nevirapine at both 200 mg twice daily and 400 mg once daily in an ethnically diverse population. HIV Med 2009; 10:310-7. [DOI: 10.1111/j.1468-1293.2008.00689.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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Wen B, Chen Y, Fitch WL. Metabolic Activation of Nevirapine in Human Liver Microsomes: Dehydrogenation and Inactivation of Cytochrome P450 3A4. Drug Metab Dispos 2009; 37:1557-62. [PMID: 19364830 DOI: 10.1124/dmd.108.024851] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Affiliation(s)
- Bo Wen
- Drug Metabolism and Pharmacokinetics, M/S S3-2-E 218, Roche Palo Alto, Palo Alto, CA 94304, USA.
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Breining A, Guihot A, Warot D, Canestri A, Peytavin G, Bricaire F, Caumes E. Persistent high nevirapine blood level with DRESS syndrome 12 days after interruption of antiretroviral therapy. BMJ Case Rep 2009; 2009:bcr07.2008.0475. [PMID: 21686791 DOI: 10.1136/bcr.07.2008.0475] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Nevirapine is an antiretroviral agent associated with drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome. Such a case in an immunocompetent woman recently treated with nevirapine for postexposure HIV prophylaxis is reported here. Despite a period of 12 days after interruption of treatment, a high blood level of nevirapine was still observed.
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Affiliation(s)
- Alice Breining
- Pitie Salpetriere Hospital, Infectious Disease, 47-83 Boulevard de l Hôpital, Paris, 75013, France
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Chen J, Mannargudi BM, Xu L, Uetrecht J. Demonstration of the metabolic pathway responsible for nevirapine-induced skin rash. Chem Res Toxicol 2008; 21:1862-70. [PMID: 18729332 DOI: 10.1021/tx800177k] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The reverse transcriptase inhibitor, nevirapine (NVP), causes skin rashes and hepatotoxicity. We used a rat model to determine if the rash is caused by the parent drug or a reactive metabolite. By manipulation of metabolic pathways and testing analogues, we eliminated all but one pathway, 12-hydroxylation, which involves the oxidation of an exocyclic methyl group, as being responsible for the rash. Treatment with 12-OH-NVP caused a rash, and an analogue in which the methyl hydrogens were replaced by deuterium to inhibit the 12-OH pathway did not cause a rash; however, quite unexpectedly, blood levels of the deuterated analogue were very low. This is due to partitioning of the benzylic free radial intermediate between oxygen rebound to form 12-OH-NVP and loss of another hydrogen atom to form a reactive quinone methide, which inactivates P450. Cotreatment with the P450 inhibitor, 1-aminobenzotriazole, led to comparable levels of NVP and the deuterated analogue, and the deuterated analogue still caused a lower rash incidence. These data clearly point to the 12-hydroxy pathway being responsible for NVP skin rash. We propose that the hepatotoxicity of NVP in humans is due to the quinone methide formed by P450 in the liver, while the skin rash may be due to the quinone methide formed in the skin by sulfation of 12-OH metabolite followed by loss of sulfate. This is the first example in which a valid animal model of an idiosyncratic drug reaction was used to determine the metabolic pathway responsible for the reaction.
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Affiliation(s)
- Jie Chen
- Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
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Current awareness: Pharmacoepidemiology and drug safety. Pharmacoepidemiol Drug Saf 2008. [PMID: 18533281 PMCID: PMC7167700 DOI: 10.1002/pds.1487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
In order to keep subscribers up‐to‐date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of pharmacoepidemiology and drug safety. Each bibliography is divided into 20 sections: 1 Reviews; 2 General; 3 Anti‐infective Agents; 4 Cardiovascular System Agents; 5 CNS Depressive Agents; 6 Non‐steroidal Anti‐inflammatory Agents; 7 CNS Agents; 8 Anti‐neoplastic Agents; 9 Haematological Agents; 10 Neuroregulator‐Blocking Agents; 11 Dermatological Agents; 12 Immunosuppressive Agents; 13 Autonomic Agents; 14 Respiratory System Agents; 15 Neuromuscular Agents; 16 Reproductive System Agents; 17 Gastrointestinal System Agents; 18 Anti‐inflammatory Agents ‐ Steroidal; 19 Teratogens/fetal exposure; 20 Others. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted.
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