High incidence of nevirapine-associated rash in HIV-infected Chinese

Singularities of nevirapine metabolism: from sex-dependent differences to idiosyncratic toxicity

Nevirapine (NVP) is a first-generation non-nucleoside reverse transcriptase inhibitor widely used for the treatment and prophylaxis of human immunodeficiency virus infection. The drug is taken throughout the patient's life and, due to the availability of an extended-release formulation, it is administered once daily. This antiretroviral is one of the scarce examples of drugs with prescription criteria based on sex, in order to prevent adverse reactions. The therapy with NVP has been associated with potentially life-threatening liver and idiosyncratic skin toxicity. Multiple evidence has emerged regarding the formation of electrophilic NVP metabolites as crucial for adverse idiosyncratic reactions. The formation of reactive metabolites that yield covalent adducts with proteins has been demonstrated in patients under NVP-based treatment. Interestingly, several pharmacogenetic- and sex-related factors associated with NVP toxicity can be mechanistically explained by an imbalance toward increased formation of NVP-derived reactive metabolites and/or impaired detoxification capability. Moreover, the haptenation of self-proteins by these reactive species provides a plausible link between NVP bioactivation and immunotoxicity, further supporting the relevance of this toxicokinetics hypothesis. In the current paper, we review the existing knowledge and recent developments on NVP metabolism and their relation to NVP toxicity.

Differences in nevirapine biotransformation as a factor for its sex-dependent dimorphic profile of adverse drug reactions

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.

Nevirapine hypersensitivity

Treatment of HIV-1 infections with nevirapine is associated with skin and liver toxicity. These two organ toxicities range from mild to severe, in rare cases resulting in life-threatening liver failure or toxic epidermal necrolysis. The study of the mechanistic steps leading to nevirapine-induced skin rash has been facilitated by the discovery of an animal model in which nevirapine causes a skin rash in rats that closely mimics the rash reported in patients. The similarity in characteristics of the rash between humans and rats strongly suggests that the basic mechanism is the same in both. The rash is clearly immune-mediated in rats, and partial depletion of CD4(+) T cells, but not CD8(+) T cells, is protective. We have demonstrated that the rash is related to the 12-hydroxylation of nevirapine rather than to the parent drug. This is presumably because the 12-hydroxy metabolite can be converted to a reactive quinone methide in skin, but that remains to be demonstrated. Although the rash is clearly related to the 12-hydroxy metabolite rather than the parent drug, cells from rechallenged animals respond ex vivo to the parent drug by producing cytokines such as interferon-gamma with little response to the 12-hydroxy metabolite, even when the rash was induced by treatment with the metabolite rather than the parent drug. This indicates that the response of T cells in vitro cannot be used to determine what caused an immune response. We are now studying the detailed steps by which the 12-hydroxy metabolite induces an immune response and skin rash. This animal model provides a unique tool to study the mechanistic details of an idiosyncratic drug reaction; however, it is likely that there are significant differences in the mechanisms of different idiosyncratic drug reactions, and therefore the results of these studies cannot safely be generalized to all idiosyncratic drug reactions.

HLA-Cw*04 allele associated with nevirapine-induced rash in HIV-infected Thai patients

Background

A high incidence of rash has been reported in HIV-1 patients who received the anti-retroviral drug nevirapine. In addition, several studies have suggested that polymorphisms of human leukocyte antigen (HLA) genes may play important roles in nevirapine-induced rash. The aim of the present study was to evaluate the effects of different HLA-C alleles on rash associated with nevirapine in patients who started highly active anti-retroviral therapy (HAART) containing nevirapine in Thailand.

Results

A case-control study was carried out involving HIV-1 patients under treatment at Bamrasnaradura Infectious Diseases Institute, Nonthaburi, Thailand between March 2007 and March 2008. The study included all HIV/AIDS patients being treated with nevirapine-containing regimens. The study population comprised 287 HIV/AIDS patients of whom 248 were nevirapine-tolerant and 39 developed rash after nevirapine treatment. From the nevirapine-tolerant patients, 60 were selected as the control group on the basis of age, sex, and therapy history matched for nevirapine-induced rash cases. We observed significantly more HLA-Cw*04 alleles in nevirapine-induced rash cases than in nevirapine-tolerant group, with frequencies of 20.51% and 7.50%, respectively (P = 0.009). There were no significant differences between the rash and tolerant groups for other HLA-C alleles except for HLA-Cw*03 (P = 0.015).

Conclusion

This study suggests that HLA-Cw*04 is associated with rash in nevirapine treated Thais. Future screening of patients' HLA may reduce the number of nevirapine-induced rash cases, and patients with alleles associated with nevirapine-induced rash should be started on anti-retroviral therapy without nevirapine.

Risk factors for treatment-limiting toxicities in patients starting nevirapine-containing antiretroviral therapy

BACKGROUND

This collaboration of seven observational clinical cohorts investigated risk factors for treatment-limiting toxicities in both antiretroviral-naive and experienced patients starting nevirapine-based combination antiretroviral therapy (NVPc).

METHODS

Patients starting NVPc after 1 January 1998 were included. CD4 cell count at starting NVPc was classified as high (>400/microl/>250/microl for men/women, respectively) or low. Cox models were used to investigate risk factors for discontinuations due to hypersensitivity reactions (HSR, n = 6547) and discontinuation of NVPc due to treatment-limiting toxicities and/or patient/physician choice (TOXPC, n = 10,186). Patients were classified according to prior antiretroviral treatment experience and CD4 cell count/viral load at start NVPc. Models were stratified by cohort and adjusted for age, sex, nadir CD4 cell count, calendar year of starting NVPc and mode of transmission.

RESULTS

Median time from starting NVPc to TOXPC and HSR were 162 days [interquartile range (IQR) 31-737] and 30 days (IQR 17-60), respectively. In adjusted Cox analyses, compared to naive patients with a low CD4 cell count, treatment-experienced patients with high CD4 cell count and viral load more than 400 had a significantly increased risk for HSR [hazard ratio 1.45, confidence interval (CI) 1.03-2.03] and TOXPC within 18 weeks (hazard ratio 1.34, CI 1.08-1.67). In contrast, treatment-experienced patients with high CD4 cell count and viral load less than 400 had no increased risk for HSR 1.10 (0.82-1.46) or TOXPC within 18 weeks (hazard ratio 0.94, CI 0.78-1.13).

CONCLUSION

Our results suggest it may be relatively well tolerated to initiate NVPc in antiretroviral-experienced patients with high CD4 cell counts provided there is no detectable viremia.

Diagnosis and management of HIV drug hypersensitivity

Drug hypersensitivity reactions are an important cause of morbidity in HIV-infected patients who take complex medication regimens. Correct diagnosis and management of these reactions are essential in the clinical care of HIV disease. Trimethoprim-sulfamethoxazole, abacavir, nevirapine, atazanavir, and enfuvirtide can all cause hypersensitivity rashes. In this review, we discuss the evidence for immunologic mechanisms of hypersensitivity reactions to HIV medications, the clinical characteristics of these reactions, and guidelines that currently exist for their identification and management.

Nevirapine-associated toxicity in HIV-infected Thai men and women, including pregnant women

OBJECTIVES

The aim of the study was to determine the incidence of, and risk factors for, nevirapine (NVP)-associated hepatotoxicity and rash in HIV-infected Thai men and women, including pregnant women, receiving NVP-containing highly active antiretroviral therapy (HAART).

METHODS

NVP-containing HAART was prescribed to eligible men and women enrolled in the Prevention of Mother-To-Child Transmission of HIV (PMTCT) and MTCT-Plus programmes. All pregnant women received zidovudine (ZDV)/lamivudine (3TC)/NVP from >14 weeks of gestational age if their CD4 cell count was <or=200 cells/microL or from >28 weeks if their CD4 cell count was >200 cells/microL. Patients followed for at least 8 weeks after starting HAART or until delivery were included in the analyses.

RESULTS

Of 409 patients, 244 were pregnant women, 87 were nonpregnant women and 78 were men. Hepatotoxicity occurred in 15.6% of all patients. Men had a significantly higher rate of asymptomatic hepatotoxicity (P=0.021). Pregnant women receiving HAART for PMTCT (92% had CD4 cell counts >250 cells/microL) had a significantly higher rate of symptomatic hepatotoxicity (P=0.0003) than pregnant women receiving HAART for therapy. Rash occurred in 16.1% of all patients. The patients' sex and baseline CD4 cell count were not associated with the risk of hepatotoxicity or rash. NVP was discontinued in 4.2% and 6.8% of patients because of hepatotoxicity and rash, respectively.

CONCLUSIONS

The incidence of NVP-related hepatotoxicity and rash in Thai adults is similar to incidences reported for other populations. While larger studies are needed, our data support continued use of NVP-containing regimens as first-line treatment in developing countries for HIV-infected patients, including pregnant women. Pregnant women with high CD4 cell counts may experience higher rates of symptomatic hepatotoxicity and thus require careful clinical and laboratory monitoring.

Is it safe to switch between efavirenz and nevirapine in the event of toxicity?

The non-nucleoside reverse transcriptase inhibitors (NNRTIs) efavirenz and nevirapine are chemically distinct, but both may cause cutaneous hypersensitivity and hepatotoxicity. We reviewed the literature to assess the evidence for cross-reactivity between nevirapine and efavirenz. All papers, abstracts, or presentations, regardless of study design, that made reference to the response of patients who were switched from one NNRTI to another as a result of an adverse drug reaction were included. Most of the studies were retrospective. Recurrent reactions occurred in 30 (12.6%) of 239 reported patients with rash who were switched from nevirapine to efavirenz, compared with eight (50%) of 16 patients switched from efavirenz to nevirapine. Hepatitis did not recur in either the 11 reported patients switched from nevirapine to efavirenz, or in the single reported patient who was switched from efavirenz to nevirapine. Substituting efavirenz for nevirapine following hepatotoxicity or cutaneous hypersensitivity appears to be reasonable, providing that the adverse reaction to nevirapine was not life-threatening. There is insufficient evidence to recommend substituting nevirapine for efavirenz following either hepatotoxicity or cutaneous hypersensitivity.

Reacciones de hipersensibilidad a antirretrovirales en pacientes con infección por el virus de la inmunodeficiencia humana

Drug hypersensitivity reactions in the HIV-positive patient are a major problem in management of these patients and, nowadays the antiretroviral agents are the main cause of those reactions, exceeding cotrimoxazole. The present review focuses on immunologic reactions that have been reported associated with antiretroviral agents. We have reviewed case reports on Medline(R) to September 2005. Evidence that these reactions are immune mediated is largely based on the typical symptomatology and few studies have been done to determine the pathogenesis mechanisms. The clinical management of this type of reactions is complex because of differential diagnosis and of potential severity. It is essential that research is now carried out into the pathogenic mechanisms and so, we shall be able to offer an efficacious protocol to manage these situations.

Toxidermie à la névirapine

BACKGROUND

Several studies have shown a high prevalence of rash induced by nevirapine. However, there is little knowledge about the risk factors associated with nevirapine-induced rash. The aim of this study was to identify risk factors associated with the occurrence of rash during the treatment with nevirapine of HIV-infected patients.

METHODS

A retrospective study was conducted in the dermatology department of Besançon university teaching hospital between November 1998 and September 2001. The study included all HIV-infected patients receiving HAART regimens that included nevirapine. The following data were collected: age, sex, CDC classification of HIV, CD4 and CD8 lymphocyte counts, plasma HIV RNA load, hepatitis B, C and cytomegalovirus serostatus, history of drug allergy, concomitant medication (other antiretroviral drugs, corticosteroids, antihistamines). Univariate analysis was performed using a Chi2 test or Fischer's test and Student's t test. Fischer's test and the Cox proportional hazards model were used in the multivariate analysis.

RESULTS

During the study period, 101 HIV-infected patients (74 men and 27 women; mean age: 41.6 +/- 10.3 years) were treated with HAART regimens including nevirapine. Fourteen developed cutaneous drug-reactions attributable to nevirapine (13.86%). We observed 13 cases of maculopapular exanthema and 1 case of DRESS. In the univariate analysis, female gender (p=0.002), plasma HIV RNA load > 10,000 copies/ml (p=0.05), heterosexual transmission (p=0.002) and abacavir treatment (p=0.05) constituted risk factors associated with rash. In the multivariate analysis, only female gender (p<0.0001) and plasma HIV RNA load > 10,000 copies/ml (p=0.0007) were associated with rash.

DISCUSSION

The results of this study confirm the high frequency of toxidermy associated with nevirapine therapy. The risk factors associated with occurrence of rash due to nevirapine therapy were female gender and plasma RNA > 10,000 copies/ml. Several studies showed absence of any protective effect of antihistamines and corticosteroids in preventing the cutaneous adverse reactions associated with nevirapine. The identification of risk factors closely associated with nevirapine-induced rash could help physicians determine new strategies for safer use of nevirapine in the HAART regimen.

Incidence and risk factors for rash in Thai patients randomized to regimens with nevirapine, efavirenz or both drugs

OBJECTIVE

To determine the incidence and risk factors for rash in Thai patients taking four different non-nucleoside reverse transcriptase inhibitor (NNRTI)-based regimens.

METHODS

HIV-positive, antiretroviral-naive patients enrolled in the 2NN study in Thailand and followed for at least 1 week were included. Patients were randomized to efavirenz (EFV) 600 mg once daily (OD) versus nevirapine (NVP) 200 mg twice daily (BD) versus NVP 400 mg OD versus NVP 400 mg OD + EFV 800 mg OD with stavudine/lamivudine.

RESULTS

Of 202 patients, 95 (47%) and 69 (34.2%) developed a rash from all reasons and from NNRTI, respectively. For NNRTI-related rash the incidences were EFV (20%), NVP BD (21%), NVP OD (38%) and NVP + EFV (67%). The proportions of patients with grade I, II and III within the four treatment arms are as follows: EFV, 4.3, 13 and 2.9%; NVP BD, 2.3, 15.9 and 2.3%; NVP OD, 12.8, 19.1 and 6.4%; and NVP + EFV, 11.9, 47.6 and 7.1%. Multivariate analyses showed females with CD4 cell count > or =250 x 10 cells/l, high body mass index (>21.3 kg/m), and a rise in CD4 (> or =53 x 10 cells/l) and alanine aminotransferase (ALT) (> or =34 U/l) at week 4 to be risk factors for rash.

CONCLUSIONS

Thai patients had a high incidence of NNRTI-related rash when treated with NVP + EFV or NVP OD. NVP if used BD had the same rash incidence as EFV for rash of all grades. Females, and persons with earlier HIV disease or with a large rise in CD4+ cell count after starting therapy are at greater risk for NNRTI-related rash.

Failure of Cetirizine to Prevent Nevirapine-Associated Rash

OBJECTIVES

Rash is the most frequent adverse event associated with nevirapine. The use of antihistamines remains unclear in this setting. A double-blind placebo-controlled study was performed to evaluate the efficacy of cetirizine in the prevention of nevirapine rash.

METHODS

A multicenter, randomized, double-blind, placebo-controlled clinical trial with cetirizine (10 mg/d x 30 days) was conducted. Inclusion criteria were HIV-1 infection and nevirapine therapy started with any CD4 cell count or plasma viral load and without simultaneous use of abacavir, cotrimoxazole, or rifampin. Clinical follow-up was performed at 15, 30, and 90 days.

RESULTS

Two hundred seventeen evaluable patients were enrolled (107 patients receiving cetirizine and 110 patients receiving placebo), 32.3% of whom were women. The median baseline CD4 cell count and plasma viral load were 341 cells/mm and 11,000 copies/mL, respectively. Overall, 29 rashes (13.4%) were detected: 16 (15.0%) in the cetirizine group and 13 (11.8%) in the placebo group (odds ratio [OR] = 1.31, 95% confidence interval [CI]: 0.60-2.88; P = 0.50). The incidence of moderate to severe rashes leading to nevirapine withdrawal was 10.3% (11 of 107 patients) in the cetirizine group and 7.3% (8 of 110 patients) in the placebo group (OR = 1.46, 95% CI: 0.52-4.18; P = 0.43). Adverse events leading to withdrawal of therapy appeared in 14 patients (13.1%) from the cetirizine group and 10 (9.1%) from the placebo group (P = 0.34).

CONCLUSION

Cetirizine does not prevent the incidence or affect the severity of nevirapine-associated rash.

HIV/AIDS in Asia

HIV (ie, HIV-1) epidemics in Asia show great diversity, both in severity and timing. But epidemics in Asia are far from over and several countries including China, Indonesia, and Vietnam have growing epidemics. Several factors affect the rate and magnitude of growth of HIV prevalence, but two of the most important are the size of the sex worker population and the frequency with which commercial sex occurs. In view of the present state of knowledge, even countries with low prevalence of infection might still have epidemics affecting a small percentage of the population. Once HIV infection has become established, growing needs for care and treatment are unavoidable and even the so-called prevention-successful countries of Thailand and Cambodia are seeing burgeoning care needs. The manifestations of HIV disease in the region are discussed with the aim of identifying key issues in medical management and care of HIV/AIDS. In particular, issues relevant to developing appropriate highly active antiretroviral treatment programmes in the region are discussed. Although access to antiretroviral therapy is increasing globally, making it work effectively while simultaneously expanding prevention programmes to stem the flow of new infections remains a real challenge in Asia. Genuine political interest and commitment are essential foundations for success, demanding advocacy at all levels to drive policy, mobilise sufficient resources, and take effective action.

Cutaneous manifestations of antiretroviral therapy

The pandemic created by HIV, a retrovirus, has stimulated increased research in viral diseases and has generated greater interest in the development of antiretroviral medications. These new medications are presently divided into 3 categories: protease inhibitors (PIs), non-nucleoside reverse transcriptase inhibitors (NNRTIs), and nucleoside reverse transcriptase inhibitors (NRTIs). These antiretroviral agents carry their own risk for causing adverse reactions, as well as drug interactions. The most recently approved class of antiretrovirals, PIs have been associated with lipodystrophy syndrome, hypersensitivity reactions, urticaria, morbilliform eruptions, and a large number of drug interactions. NNRTIs have resulted in various cutaneous eruptions, as well as a hypersensitivity syndrome. NRTIs have resulted in alterations of the nails, nail and mucocutaneous pigmentation, hair changes, vasculitis, and morbilliform eruptions. This article focuses on the cutaneous manifestations of antiretroviral therapy to help dermatologists recognize them.

Jaundice and hepatocellular damage associated with nevirapine therapy

OBJECTIVE

Nevirapine is a nonnucleoside reverse transcription inhibitor that is used as part of highly active antiretroviral therapeutic combinations. Nevirapine has been associated with a skin rash in 32 to 48% of patients. Recent reports indicate that hepatic toxicity also occurs.

METHODS

We describe four instances of reversible hepatocellular damage associated with the use of nevirapine in patients with HIV infection. Two of the four patients were also coinfected with the hepatitis C virus.

RESULTS

Evidence of malaise, skin rash, and icteric hepatitis with pruritus occurred 4-6 wk after the beginning of nevirapine therapy. No evidence of metabolic acidosis was present in any of our patients. In all cases, liver test results declined to normal or near normal levels, and pruritus disappeared 4-6 wk after discontinuation of the medication. No patient was rechallenged with the drug.

CONCLUSION

Nevirapine can be associated with icteric hepatitis, which appears to be reversible after withdrawal of the drug.