Drug-induced liver injury associated with the use of nonnucleoside reverse-transcriptase inhibitors

Determinants of nevirapine hypersensitivity and its effect on the association between hepatitis C status and mortality in antiretroviral drug-naive HIV-positive patients

OBJECTIVE

To assess risks factors and outcomes associated with nevirapine hypersensitivity reactions, and to determine the effect of hypersensitivity as a modifier of the association between hepatitis C virus (HCV) infection and mortality among antiretroviral drug-naive patients.

METHODS

The primary endpoint was hypersensitivity reactions in a population-based cohort of antiretroviral therapy-naive HIV-individuals, 18 years or older in British Columbia, Canada, who started triple antiretroviral therapy with nevirapine between May 1997 and June 2003. Univariate and multivariate analyses were performed to identify predictors of nonaccidental mortality in the subgroup of patients with known HCV serostatus.

RESULTS

A total of 66 (9.6%) of 685 patients met the definition for hypersensitivity reactions. In the univariate logistic regression analysis, no variables were identified as risk factors. In multivariate survival analyses conducted to identify characteristics associated with nonaccidental mortality, patients with both HCV coinfection and hypersensitivity reactions had a higher risk of death (hazard ratio, 7.12; 95% confidence interval, 2.73-18.53; P < 0.001) compared with those who did not have HCV coinfection or hypersensitivity reaction.

CONCLUSION

Results of this study suggest that the hypersensitivity reaction behaves as an effect modifier of the association between HCV infection and mortality in this cohort of antiretroviral drug-naive HIV-positive patients. These results support the current recommendation against the use of nevirapine in HIV/HCV-coinfected patients.

Hepatotoxicity in an African antiretroviral therapy cohort: the effect of tuberculosis and hepatitis B

OBJECTIVE

Hepatotoxicity is a significant complication of antiretroviral therapy (ART). We assessed the incidence of and risk factors for hepatotoxicity among HIV-infected individuals on ART in South Africa.

DESIGN

We conducted a retrospective cohort study in a workplace HIV care program in South Africa which uses a first-line regimen of efavirenz, zidovudine, and lamivudine and provides routine clinical and laboratory monitoring.

METHODS

We included subjects with baseline and follow-up alanine transaminase and aspartate aminotransferase tests. Severe hepatotoxicity cases were identified during the first 12 months of ART. Potential risk factors, including concomitant medication use, tuberculosis, and hepatitis B and C, were determined from clinical records, database queries, and serological testing. Associations with hepatotoxicity were investigated using Cox proportional hazards modeling.

RESULTS

Of the 868 subjects (94% male, median age 41 years), the median nadir CD4 cell count was 136/microl, 25% received concomitant tuberculosis treatment during ART, and 17% of a randomly selected subset were positive for hepatitis B surface antigen (HBsAg). We identified 7.7 episodes of severe hepatotoxicity per 100 person-years. Tuberculosis treatment increased risk 8.5 fold, positive HBsAg 3.0 fold, and nadir CD4 cells count < 100/microl 1.9 fold. Importantly, the fraction of patients with severe hepatotoxicity on ART (4.6%) was similar to the fraction with liver enzyme elevations > 5 times the upper limit of normal before starting ART (4%).

CONCLUSIONS

In this African ART cohort, we found a low incidence of and minimal morbidity due to hepatotoxicity. HBsAg and concomitant tuberculosis therapy significantly increased the risk of hepatotoxicity.

Pharmacogenetic Considerations in the Management of HIV Infection

Potent combination antiretroviral drug therapy has now been available to HIV-infected patients for more than a decade, resulting in a significant decline in disease-related morbidity and mortality. Nonetheless, a number of HIV-infected individuals fail to experience the full benefit of their antiretroviral medications; some lack a robust virologic response, while others experience treatment-limiting toxicities. A number of factors may contribute to variable drug response in patients with HIV infection. Virologic, immunologic, pharmacologic, and pharmacokinetic differences between HIV-infected patients have all been noted to contribute to interpatient variability in drug response. Recent data suggest that pharmacogenetic differences among HIV-infected individuals may also be an important variable that contributes to antiretroviral drug response. Pharmacogenetic studies of antiretroviral drug therapy have explored the influence of single nucleotide polymorphisms in genes responsible for key proteins involved in antiretroviral drug metabolism (cytochrome P50 enzymes) and drug transport (P-glycoprotein). In addition, the human leukocyte antigen genotype (HLA-B*57) has been found to predict abacavir-associated hypersensitivity reactions. Antiretroviral pharmacogenetics offers the possibility of optimizing virologic response and minimizing drug toxicity by individualizing anti-HIV pharmacotherapy. The authors review those genetic polymorphisms that have been shown, or are strongly suspected, to influence antiretroviral drug metabolism, transport, and toxicity.

Efavirenz: a review

Efavirenz is a non-nucleoside reverse transcriptase inhibitor that in most treatment guidelines is recommended to be taken combined with two nucleoside analogue reverse transcriptase inhibitors, as a preferred first-line regimen for the treatment of HIV-1 infection. The antiretroviral efficacy of efavirenz-based combination regimens is good, as has been demonstrated in many clinical trials. Efavirenz has a long plasma half-life, which allows for once-daily dosing, but, as a consequence of this and the low genetic barrier, it is also prone to select for viral resistance when adherence to therapy is suboptimal. The most frequently encountered side effects are neuropsychiatric symptoms. These side effects are usually transient, but have been shown to persist for up to 2 years after initiation of therapy in some patients. This review outlines important and recent pharmacological and clinical data, which explain why efavirenz became a component of preferred treatment regimens today.

Risk of Discontinuation of Nevirapine due to Toxicities in Antiretroviral-Naive and -Experienced HIV-Infected patients with High and Low CD4+ T-cell Counts

Introduction

It is unknown whether the increased risk of toxicities in antiretroviral-naive HIV-infected patients initiating nevirapine-based (NVPc) combination antiretroviral therapy (cART) with high CD4+ T-cell counts is also observed when NVPc is initiated in cART-experienced patients.

Patients and methods

1,571 EuroSIDA patients started NVPc after 1/1/1999, with CD4+ T-cell counts and viral load measured in the 6 months before starting treatment, and were stratified into four groups based on CD4+ T-cell counts at initiation of NVPc (high [H], >400/mm3 or >250/mm3 for male or female, respectively, or low [L], ≤400/mm3 or ≤250/mm3 for male or female) and prior antiretroviral experience (antiretroviral-naive [N] or -experienced [E]). Cox proportional hazards models compared the risks of discontinuation of nevirapine due to toxicities or patient/physician choice (TOXPC).

Results

After adjustment, there was a significantly lower risk of discontinuation of nevirapine due to TOXPC in the HE group ( n=588; proportion discontinued by 3/12 months: 10/17%, respectively) than in HN (n=62; 21/32% respectively; overall relative hazard [RH]: 0.56; 95% confidence interval [CI]: 0.34–0.94; P=0.027). This difference was most pronounced during the first 3 months of NVPc (RH: 0.44; 95% CI: 0.23–0.87; P=0.017). There were no deaths in the 6 months after starting NVPc resulting from exposure to <3 months of NVPc exposure within the HE group (incidence: 0; per 1,000 person-years follow up; 95% CI: 0–6.9). After adjustment, there were no differences between the HE and HN groups in discontinuation due to TOXPC in patients starting efavirenz-based cART (RH: 0.91; 95% CI: 0.60–1.38; P=0.66) or protease-inhibitor-based cART (RH: 1.13; 95% CI: 0.77–1.66; P=0.52).

Conclusions

Results from this non-randomized study suggest that NVPc might be safer to initiate in antiretro-viral-experienced than in antiretroviral-naive patients with high CD4+T-cell counts.

Is the increased risk of liver enzyme elevation in patients co-infected with HIV and hepatitis virus greater in those taking antiretroviral therapy?

OBJECTIVES

To investigate if the risk of liver enzyme elevation (LEE) in HIV/hepatitis B or C (HBV, HCV) co-infection is altered by HAART (two or more drugs).

METHODS

Analysis comprised HIV-positive patients in the ICoNA study without acute hepatitis who had >or= 1 positive HCV antibody test and > 1 positive HBV surface antigen test. LEE was defined as > 5x baseline alanine aminotransferase (ALT) or > 3.5x baseline if the baseline was > 40 IU/l. Analysis used Poisson regression with generalized estimating equation correction to examine HBV or HCV co-infection, use of HAART, baseline ALT and demographics as LEE predictors.

RESULTS

Of the 5272 patients, 47.6% were co-infected with HCV/HBV; 29.9% were female and 39% were intravenous drug users. There were 275 episodes of LEE during 18 259 person-years follow up. Taking HAART did not significantly increase risk of LEE [adjusted relative risk (RR), 1.19; 95% confidence interval (CI), 0.81-1.75; P = 0.37]. Co-infection increased the risk of LEE (adjusted RR, 5.07; 95% CI, 3.47-7.48; P < 0.001), with no significant differences if taking HAART (adjusted RR, 4.99; 95% CI, 3.38-7.37) or not (adjusted RR, 6.02; 95% CI, 2.02-17.98) (P = 0.74 for interaction). Females were at lower risk of LEE than males (adjusted RR, 0.59; 95% CI, 0.42-0.83; P = 0.02).

CONCLUSIONS

HIV and HBV/HCV co-infection per se is associated with increased risk of LEE that is not modified by HAART. The recommendation for caution in HAART use in co-infected patients, simply based on a high rate of LEE in people on therapy, may be questionable.

Liver transplantation for fulminant hepatitis related to nevirapine therapy

Drug-induced hepatotoxicity is an important cause of hepatocellular injury. Non-nucleoside retroviral transcriptase inhibitors are known to cause hepatotoxicity. We describe a detailed case of fulminant hepatitis induced by nevirapine (Viramune) and treated by liver transplantation.

Antiretroviral medication considerations for individuals coinfected with HIV and hepatitis C virus

There is great need to treat HIV/hepatitis C virus (HCV)-coinfected individuals with both antiretroviral and anti-HCV pharmacotherapy. However, treatment for HIV may lead to hepatotoxicity, and there are potential interactions and synergistic effects between antiretrovirals and anti-HCV medications. The ideal antiretroviral therapy options for coinfected patients, in the setting of anti-HCV treatment, are unclear and present important challenges to clinicians. We review the current data on the use of antiretrovirals in HIV/HCV-coinfected patients and offer evidence-based recommendations on optimal selection and dosing of antiretroviral agents for this population.

Management of antiretroviral drug toxicity

PURPOSE OF REVIEW

With the emergence of very potent antiretroviral regimens, the major limitation to the success of treatment is now the tolerability of drugs, which can ultimately affect adherence. It is important, therefore, to review the current understanding on antiretroviral drug toxicity, and examine key recent data that can inform the successful avoidance or management of such toxicities.

RECENT FINDINGS

A common theme of recent research has focussed on the genetic predisposition to important immediate side-effects, such as abacavir hypersensitivity, nevirapine hepatotoxicity, efavirenz neurotoxicity and hyperbilirubinemia with atazanavir. Long-term toxicities such as body-composition changes and hyperlipidemia have been more closely linked to thymidine analogues and certain protease inhibitors. The management of these toxicities has also been clarified by studies addressing switching antiretroviral drugs or specific treatments for metabolic syndromes.

SUMMARY

Recent data emphasize the need for the prevention of antiretroviral toxicity by the avoidance of some drugs in certain genetically predisposed populations or by the avoidance of entire classes if possible. In addition, recent studies emphasize the importance of ongoing research to determine the emergence of additional toxicities, as new drugs emerge and achieve widespread use.

HLA-dependent hypersensitivity to nevirapine in Sardinian HIV patients

BACKGROUND

Hypersensitivity reaction to nevirapine, which in some cases can be fatal, shows a higher prevalence in Sardinia in comparison with other Italian regions.

OBJECTIVE

This study demonstrates that hypersensitive reaction to nevirapine in Sardinian HIV-infected patients is associated with the HLA Cw8-B14 haplotype. These two HLA class I antigens are in strong linkage disequilibrium in the Sardinian population.

METHODS

Forty-nine Sardinian HIV-positive patients treated with nevirapine were studied. Thirteen (26%), developed a hypersensitive reaction thus requiring the drug to be discontinued. HLA class I and II molecular typing was performed in both nevirapine-hypersensitive and nevirapine-tolerant patients. To avoid biased representation of the allele frequencies in the two groups of treated patients, molecular typing was also performed in 82 HIV-positive patients who had not been treated with nevirapine.

RESULTS

Considerable overlap was observed for the clinical, immunological and demographic characteristics of the 13 hypersensitive patients and 36 tolerant patients. Clinical parameters included viral load, status of HIV infection, CD4 and CD8 cell counts, hepatitis C virus/hepatitis B virus co-infections. Forty-six percent (6/13) of the nevirapine-hypersensitive subjects had the HLA-Cw8 and HLA-B14(65) antigens compared with 5% (2/36) of the nevirapine-tolerant group (P = 0.004; Pc = 0.05).

CONCLUSION

In agreement with other recent reports, the utility of HLA typing in HIV patients to identify genetic factors that may confer susceptibility to drug-induced hypersensitive reaction was confirmed. A careful choice of antiretroviral therapy in susceptible individuals should significantly reduce the risk of severe hypersensitive reaction.

Safety of nevirapine-containing antiretroviral triple therapy regimens to prevent vertical transmission in an African cohort of HIV-1-infected pregnant women

OBJECTIVE

To assess the incidence and consequences of adverse reactions among African HIV-positive pregnant women treated with fixed-dose combinations of a nevirapine-containing antiretroviral (ARV) triple therapy.

METHODS

A retrospective analysis of the clinical files of 703 HIV-1-positive pregnant women treated with a nevirapine-containing regimen between May 2002 and July 2004 was conducted. Selection criteria for inclusion in the analysis were: (a) taking ARV for more than 14 days; (b) baseline values of transaminases below the threshold of 2.5 times the upper limit of normal (ULN). The women were on a nevirapine-containing regimen for a median of 127 days [interquartile range (IQR) 86-190 days], starting on average at the 27th week of gestation (standard deviation+/-9.5) and continuing up to a maximum of 6 months after delivery. All women were offered formula milk to feed the babies. Highly active antiretroviral therapy (HAART) was continued beyond 6 months only if the patient qualified on the first visit. The main outcome measures were incidence of hepatotoxicity, skin rashes and Stevens-Johnson syndrome. Multivariate analysis to assess the impact of several factors on the adverse reaction rate was performed.

RESULTS

As of 1 August 2004, 554 pregnancies reached term, 96 women were still pregnant, and 53 women dropped out of the programme before giving birth. After 2 months of therapy the percentage of patients with a viral load less than 1000 HIV-1 RNA copies/mL increased to 78.6%; average CD4 cell counts increased from 490 cells/microL before therapy to 630 after therapy. The incidence of grade 3-4 adverse reactions (hepatotoxicity, skin rashes and Stevens-Johnson syndrome) was 6.5, 2.4 and 1.1%, respectively. Five women died during pregnancy (0.88%). Only one of the deaths could be associated with ARV treatment.

CONCLUSION

Nevirapine-containing regimens in pregnant woman, at all CD4 cell count levels, appear to be safe in African settings.

Drug-Specific T Cells in An HIV-Positive Patient with Nevirapine-Induced Hepatitis

Background

Nevirapine is associated with idiosyncratic reactions such as skin rash, hepatitis and hypersensitivity syndrome, which have the hallmarks of being immune mediated. However, there is little laboratory evidence to support an immune pathogenesis.

Methods

A HIV-positive individual who developed hepatitis within 6 weeks of starting nevirapine, in the absence of any cutaneous manifestations, is described. Other causes of hepatitis were excluded, and the patients liver function normalized on withdrawal of nevirapine. Lymphocytes from the patient, and six individuals with HIV who were on nevirapine without adverse effects, were exposed to nevirapine and its metabolites, and lymphocyte proliferation assessed by 3H-thymidine incorporation on day 5.

Results

The T cells taken from the nevirapine-hypersensitive patient proliferated in the presence of nevirapine with a stimulation index of greater than 2. There was no proliferation with nevirapine metabolites. T cells taken from HIV-positive control individuals showed no proliferation with either nevirapine or its metabolites.

Conclusion

The results from our patient suggest that T cells may be involved in the pathogenesis of nevirapine-induced hepatitis. Larger numbers of patients need to be studied to fully evaluate the role of T cells in nevirapine-induced hepatitis and nevirapine hypersensitivity syndrome.

Treatment of hepatitis C in HIV-coinfected patients

OBJECTIVE

To review the current management of hepatitis C virus (HCV) in persons coinfected with HIV.

DATA SOURCES

A MEDLINE search (1966-February 2006) was conducted, using key words such as HIV, human immunodeficiency virus, hepatitis C, interferon, pegylated interferon, and therapy. Article bibliographies and conference abstracts were also reviewed to identify relevant studies.

STUDY SELECTION AND DATA EXTRACTION

Studies that examined HCV treatment in individuals coinfected with HIV and articles that focused on HCV/HIV coinfection were considered for this review.

DATA SYNTHESIS

Coinfection with HIV leads to a more rapid and severe course of HCV-related liver disease. Treatment of HCV with pegylated interferon (PEG-IFN) and ribavirin therapy is relatively well tolerated in individuals coinfected with HIV, with overall sustained virologic response (SVR) rates of 27-40%. High relapse rates and poor response in HCV-genotype 1 contribute to the lower SVR in coinfected individuals compared with HCV monoinfection. Treatment of HCV is more complicated in HIV-infected persons due to increased risk of myelosuppression, drug interactions, hepatotoxicity of antiretroviral therapy, and the relative contraindication to interferon therapy in advanced HIV disease. Current guidelines recommend that all HIV-positive patients with chronic HCV infection be considered as treatment candidates for anti-HCV therapy due to the higher risk of liver disease progression. Further studies are needed, however, to define the appropriate dose and duration of therapy in HCV/HIV-coinfected individuals.

CONCLUSIONS

Response to treatment with PEG-IFN and ribavirin is poorer in patients coinfected with HCV/HIV than in those infected with HCV alone. The benefits of anti-HCV therapy, including viral eradication, need to be weighed against the risks of adverse effects and drug-drug interactions between anti-HCV and antiretroviral medications.

Predicting and diagnosing abacavir and nevirapine drug hypersensitivity: from bedside to bench and back again

There is a growing discussion surrounding the issue of personalized approaches to drug prescription based on an individual's genetic makeup. This field of investigation has focused primarily on identifying genetic factors that influence drug metabolism and cellular disposition, thereby contributing to dose-dependent toxicities and/or variable drug efficacy. However, pharmacogenetic approaches have also proved valuable in predicting drug hypersensitivity reactions in selected patient populations, including HIV-infected patients receiving long-term antiretroviral therapy. In this instance, susceptibility has been strongly linked to genetic loci involved in antigen recognition and presentation to the immune system--most notably within the major histocompatibility complex (MHC) region--consistent with the notion that hypersensitivity reactions represent drug-specific immune responses that are largely dose independent. Here the authors describe their experiences with the development of pharmacogenetic approaches to hypersensitivity reactions associated with abacavir and nevirapine, two commonly prescribed antiretroviral drugs. It is demonstrated that prospective screening tests to identify and exclude individuals with a certain genetic makeup may be largely successful in decreasing or eliminating incidence of these adverse drug reactions in certain populations. This review also explores the broader implications of these findings.

Major role of hepatitis B genotypes in liver fibrosis during coinfection with HIV

BACKGROUND

Little is know about the determinants of liver fibrosis progression and genomic variability in hepatitis B virus (HBV) in HIV/HBV-coinfected patients.

METHODS

A cross-sectional analysis examined common characteristics of HBV infection in an ongoing cohort study of 308 patients with both HIV-1-positive Western blot and plasma HBV surface antigen (HBsAg) seropositivity. Risk factors for liver fibrosis were studied in a subset of 104 patients for whom liver biopsy and complete HBV genomic analysis were available. Analysis was performed by exact multiple regression analysis.

RESULTS

Mean age of the study population was 40.3 years, with a ratio male to female of 5.3 and a mean duration of HIV infection of 9.3 years. In the subset of 104 patients, plasma HBV e antigen (HBeAg) in HBV-replicative patients could not be detected in 28.4% and lamivudine-resistant mutants were detected in 67.8%. HBV genotype A was the most frequent genotype (73/104) and 25 patients were infected by the usually rare genotype G. METAVIR fibrosis score was rated F2-F4 in 70 patients. After adjustment for the most common known determinants of liver fibrosis, HBV genotype G [odds ratio (OR), 12.60; 95% confidence interval (CI), 1.72-infinite; P < 0.009], efavirenz exposure (OR, 3.55; 95% CI, 1.14-12.14; P < 0.03), and the duration of HIV infection (3.86; 95% CI, 1.27-12.64; P < 0.01) were strongly associated with the risk of grade F2-F4 fibrosis.

CONCLUSION

HBV genotype G is a determinant of liver fibrosis in HIV/HBV-coinfected patients and HBV genotyping should be considered as part of the management of patients with multiple risk factors for rapid progression of liver fibrosis.

Third-trimester maternal toxicity with nevirapine use in pregnancy

OBJECTIVE

Nevirapine-based therapy is associated with increased frequency of adverse events among women with CD4+ cell count of 250 cells/microL or greater. We evaluated the safety of nevirapine-based antiretroviral therapy in human immunodeficiency virus (HIV)-1-infected pregnant women.

METHODS

We retrospectively evaluated 23 pregnancies managed with nevirapine-based regimens from July 2001 to April 2005. The incidence of adverse events was determined and analyzed by CD4+ cell count of either less than or greater than or equal to 250 cells/microL, and gestational age when nevirapine was initiated. Liver function abnormality was graded according to the National Institute of Allergy and Infectious Diseases Division of AIDS toxicity guidelines.

RESULTS

Five of 23 patients (21.7%) started nevirapine-based therapy after 27 weeks of gestation. All 3 cases of adverse events occurred in this group within 6 weeks of initiating therapy and with CD4+ cell count greater than 250 cells/microL. A significant difference was noted in the proportion of patients who developed toxicity while starting nevirapine in the third trimester (3/5, 60%; 95% confidence interval 14.66-94.73) compared with those starting nevirapine earlier in pregnancy (0/18, 0%; 95% confidence interval 0.0-18.53; P < .006). Two patients developed rash, eosinophilia, and liver function abnormality, with one developing clinical hepatitis and renal failure. A third patient had abnormal elevation of liver enzymes but was asymptomatic.

CONCLUSION

The incidence of adverse events with nevirapine may be lower than previously reported (13% versus 29%) and may be primarily noted with initiating the drug late in pregnancy. Further study of nevirapine in larger cohorts of HIV-infected pregnant women is warranted to determine the relationship between nevirapine hepatotoxicity and trimester use.

LEVEL OF EVIDENCE

II-3.

Nevirapine toxicity in a cohort of HIV-1-infected pregnant women

OBJECTIVE

The purpose of this study was to complete an evaluation of nevirapine (NVP) toxicity in a cohort of HIV+ pregnant women.

STUDY DESIGN

This was a retrospective study of 611 women followed from January 1996 to December 2003. All women who used NVP for > 7 days were included. Multivariate logistic regression was used to test independent association of CD4 and hepatitis C virus (HCV) infection related to the outcome of toxic effects of NVP.

RESULTS

One hundred ninety-seven women were exposed to NVP for > 7 days, and toxicity occurred in 11 (5.6%), leading to drug discontinuation in 7 patients. One case of Stevens-Johnson syndrome occurred. No serious liver toxicity occurred except for 1 grade 4 cholestasis. Median CD4 was 344 in women without toxicities and 298 in women with toxicities. HCV was the only significant factor associated to toxicity by logistic regression (odds ratio [OR] 15.61, P = .001).

CONCLUSION

NVP toxicities occurred in a very small fraction of patients and were not associated with fatalities.

HIV and liver diseases: recent clinical advances

Because the life expectancy of patients infected with HIV has been prolonged, liver diseases have assumed far greater importance as a cause of morbidity and mortality in these patients. Given the shared risks of transmission, patients who have HIV often are coinfected with hepatotrophic viruses such as hepatitis C and hepatitis B. Further, antiretroviral therapy (ART) used by patients who have HIV is often hepatotoxic, contributing to liver damage. With increasing immunosuppression caused by AIDS, patients who have HIV have to deal with these issues and the increased risk of infection with opportunistic viral, fungal, bacterial, and protozoal pathogens. In addition, steatosis and lipodystrophy now are recognized more commonly in patients who have HIV, particularly in the setting of ART. Thus, understanding of liver diseases in the setting of HIV infection becomes an important focus in caring these individuals. There have been numerous advances in the treatment of liver disease in patients who have HIV, particularly in treating viral hepatitis C and B. This article reviews various liver manifestations in patients who have HIV and the recent advances in diagnostic and therapeutic options.

Management of HIV Infection in Persons Co-infected With Hepatitis

Co-infection with hepatitis C virus (HCV) and/or hepatitis B virus (HBV) is becoming a rampant disparity in HIV-infected patients. The advent of antiretroviral therapy has led to agents that are effective for suppression of both HIV and HBV; however, this can not be extrapolated to patients who are coinfected with HCV. Treatment of HCV disease is often strenuous and can lead to untoward adverse effects. Co-infection with HIV often leads to higher rates of cirrhosis and liver failure in patients with HBV or HCV, compromising antiretroviral treatment in this patient population due to the hepatotoxicity of these agents. The purpose of this review is to familiarize health care providers to the management of HIV infection in patients who are also co-infected with HBV or HCV.

Incidence and risk factors for liver enzyme elevation during highly active antiretroviral therapy in HIV-HCV co-infected patients: results from the Italian EPOKA-MASTER Cohort

BACKGROUND

The risk of hepatotoxicity associated with different highly active antiretroviral therapy (HAART) regimens (containing multiple-protease inhibitors, single-protease inhibitors or non nucleoside reverse transcriptase inhibitors) in HIV-HCV co-infected patients has not been fully assessed.

METHODS

Retrospective analysis of a prospective cohort of 1,038 HIV-HCV co-infected patients who commenced a new HAART in the Italian MASTER database. Patients were stratified into naïve and experienced to antiretroviral therapy before starting the study regimens. Time to grade > or =III hepatotoxicity (as by ACTG classification) was the primary outcome. Secondary outcome was time to grade IV hepatotoxicity.

RESULTS

Incidence of grade > or =III hepatotoxicity was 17.71 per 100 patient-years (p-yr) of follow up in naïve patient group and 8.22 per 100 p-yrs in experienced group (grade IV: 4.13 per 100 p-yrs and 1.08 per 100 p-yrs, respectively). In the latter group, the only independent factors associated with shorter time to the event at proportional hazards regression model were: previous liver transaminase elevations to grade > or =III, higher baseline alanine amino-transferase values, and use of a non nucleoside reverse transcriptase inhibitor based regimen. In the naive group, baseline aspartate transaminase level was associated with the primary outcome.

CONCLUSION

Use of a single or multiple protease inhibitor based regimen was not associated with risk of hepatotoxicity in either naïve or experienced patient groups to a statistically significant extent. A cautious approach with strict monitoring should be applied in HIV-HCV co-infected experienced patients with previous liver transaminase elevations, higher baseline alanine amino-transferase values and who receive regimens containing non nucleoside reverse transcriptase inhibitors.

Efficacy and Safety of Once-Daily Combination Therapy with Didanosine, Lamivudine and Nevirapine in Antiretroviral-Naive HIV-Infected Patients

Background

Simplified antiretroviral regimens are needed to improve patient adherence and quality of life. The purpose of this study was to evaluate the efficacy and safety of a once-daily regimen consisting of didanosine (ddI), lamivudine (3TC) and nevirapine (NVP) for adult antiretroviral-naive patients with HIV-1 infection.

Methods

This was a prospective, one-arm, multicentre pilot study. Daily drug dosage was 250 or 400 mg didanosine, 300 mg lamivudine and 400 mg nevirapine. The primary outcome measure was the percentage of patients with a plasma HIV-RNA level <50 copies/ml at 12 months on an intention-to-treat (ITT) basis.

Results

Seventy patients were enrolled in the study. At baseline, mean plasma HIV-1 RNA was 5.10 log10 copies/ml, and mean CD4 cell count was 262 cells/μl. At month 12, 67% (95% CI: 56–78) of patients maintained a viral load of <50 copies/ml in the ITT analysis and CD4 counts increased a median of 201 cells/μl. The treatment was more effective in patients with baseline CD4 counts >100 cells/μl than in those with a poorer immunological status at baseline, although the number of patients with CD4 counts <100 was low. Four patients died during the study period. Therapy was discontinued in 18 patients due to virological failure in 11, adverse events in seven, loss to follow-up or withdrawal of consent in four and death in one. Eight out of nine patients with available genotype after virological failure showed resistance mutations to NVP (Y181C and others) and 3TC (M184V/I), and four of them also had ddI resistance (L74V). The lipid profile was favourable, with a decrease in the ratio of total-to-high density lipoprotein cholesterol.

Conclusion

A once-daily combination of ddI, 3TC and NVP seems to be an effective, safe and easy-to-take regimen in antiretroviral-naive patients, at least in those who do not have severe immunodepression at baseline.

Drug-induced liver disease 2004

PURPOSE OF REVIEW

To summarize the salient reviews, studies and case reports and series that dealt with clinical, pathological, methodological, and epidemiological descriptions of drug-induced liver disease in the calendar year 2004.

RECENT FINDINGS

While no new causes of drug-induced liver injury were reported for 2004, several new reports of previously recognized hepatotoxins, including herbal products, were published. These include the antiretroviral drugs for HIV and agents to manage tuberculosis. Acetaminophen (APAP) retained its preeminent position as the leading cause of drug-induced acute liver failure, currently accounting for nearly 50% of cases according to the latest figures from the U.S. Acute Liver Failure Study Group. Not surprisingly, APAP also heads the list of drugs and toxins leading to liver transplantation for acute hepatic failure. Efforts to reduce the number of cases of intentional APAP poisonings by restricting the number of tablets sold at any one time in the UK are ongoing, but the success of the program may be lessening, as was pointed out this year. The use of potentially hepatotoxic medications in patients with underlying liver disease was examined with the statins, and they emerged as a safe class for use in this setting.

SUMMARY

Given the apparent increasing incidence of acute liver failure attributable to APAP in the US, additional efforts are still needed to better define the risks associated with its use and to further reduce the incidence of severe liver injury from this widely used agent.

Antiretroviral-associated hepatotoxicity

The use of highly active antiretroviral therapy has dramatically reduced HIV-associated morbidity and mortality. As a result, patients are often being treated longer and with more complex medical regimens than ever before, increasing the risk for drug interactions and toxicities. In particular, hepatotoxicity caused by antiretroviral use has become an increasingly appreciated potential complication of drug treatment. All classes of antiretrovirals have been reported to induce liver enzyme abnormalities. However, certain antiretrovirals appear much more likely to be associated with drug-induced hepatotoxicity. The risk of antiretroviral-related hepatotoxicity may be associated with patient-specific risk factors, including pre-existing viral hepatitis, baseline elevated liver function test results, female gender, and substance abuse. In addition, complex drug-drug interactions may potentate the risk of antiretroviral-associated hepatotoxicity. Coinfection with hepatitis B or hepatitis C appears to increase the risk of antiretroviral-related hepatotoxicity.

Progression of liver fibrosis in patients coinfected with hepatitis C virus and human immunodeficiency virus undergoing antiretroviral therapy

As the immunosuppression caused by human immunodeficiency virus (HIV) accelerates the progression of hepatitis C virus (HCV)-related liver fibrosis, the immune reconstitution associated with highly active antiretroviral therapy (HAART) may have the opposite effect. However, hepatotoxicity related to HAART could enhance the progression of liver fibrosis. Some retrospective studies have shown that therapy with the protease inhibitors may be associated with less severe liver fibrosis, whereas nevirapine use seems to correlate with faster progression. Low-grade liver toxicity associated with nevirapine could account for this effect. However, other studies have not confirmed these findings. Long-term prospective studies are needed to analyse the impact of antiretroviral drugs on the progression of HCV-related liver disease. Meanwhile, no specific recommendations can be made on the use of individual drugs or drug classes in HIV/HCV-coinfected patients. Most importantly however, the inherent benefits of HAART largely outweigh the risk of enhancing fibrosis progression. Additionally, in coinfected patients, other factors that promote fibrogenesis, such as alcohol consumption, should be avoided. Antiviral treatment of chronic hepatitis C could also reduce the risk of liver damage associated with HAART.

Influence of liver fibrosis on highly active antiretroviral therapy-associated hepatotoxicity in patients with HIV and hepatitis C virus coinfection

BACKGROUND

Coinfection with hepatitis C virus (HCV) and human immunodeficiency virus (HIV) is a known risk factor for hepatotoxicity in patients receiving highly active antiretroviral therapy (HAART). The aim of this study was to evaluate the role of HCV-related liver fibrosis in HAART-associated hepatotoxicity.

METHODS

In a prospective study involving 107 patients who underwent liver biopsy, fibrosis was graded according 5 stages, from F0 (no fibrosis) to F4 (cirrhosis). Hepatotoxicity was defined as an increase in levels of aspartate aminotransferase and alanine aminotransferase to >5 times the upper limit of normal, or a >3.5-fold increase if baseline levels were abnormal. The incidence of hepatotoxicity was compared with liver fibrosis stage and with time and composition of HAART.

RESULTS

Overall, 27 patients (25%) had hepatotoxic events (5.1 events/100 person-years of therapy). The incidence was greater for patients with stage F3 or F4 fibrosis (38%) than for those with stage F1 or F2 fibrosis (15%; 7.6 vs. 3 events/100 person-years; relative risk, 2.75; 95% confidence interval, 1.08-6.97; P=.013). Duration of HCV infection, duration of HAART, diagnosis of acquired immunodeficiency syndrome, HCV load, HCV genotype, and nadir CD4(+) cell count did not affect the risk of hepatotoxicity. Of the 86 patients who received nonnucleoside reverse-transcriptase inhibitors (NNRTIs), 11 (13%) developed liver toxicity. In these patients, fibrosis stages F1 and F2 were associated with similar rates of toxicity (3 events/100 person-years for patients who received nevirapine, 3.3 events/100 person-years for those who received efavirenz, and 3.4 events/100 person-years for those who received non-NNRTIs). There was a greater incidence among patients with F3 or F4 fibrosis who received NNRTIs (11.7 events/100 person-years for patients who received nevirapine, and 8.6 events/100 person-years for those who received efavirenz), compared with those who received non-NNRTIs (4 events/100 person-years).

CONCLUSIONS

HAART-associated hepatotoxicity correlates with liver histological stage in patients coinfected with HIV and HCV. There was no difference in hepatotoxicity risk for different antiretroviral therapies in patients with mild-to-moderate fibrosis.

Predisposition to nevirapine hypersensitivity associated with HLA-DRB1*0101 and abrogated by low CD4 T-cell counts

Genetic (human leukocyte antigen), disease-related and demographic risk factors for nevirapine reactions were examined in a nevirapine-exposed cohort. Cases involving combinations of hepatitis, fever or rash were associated with an interaction between HLA-DRB1*0101 and the percentage of CD4, whereas no associations were detected for isolated rash. These data suggest that HLA-DRB1*0101 and the CD4 status may determine susceptibility to nevirapine hypersensitivity, consistent with a CD4 T-cell-dependent immune response to nevirapine-specific antigens.

Adverse hepatic drug reactions: inflammatory episodes as consequence and contributor

Susceptibility to drug toxicity is influenced by a variety of factors, both genetic and environmental. The focus of this article is the evidence addressing the hypothesis that inflammation is both a result of and a susceptibility factor for drug toxicity, with an emphasis on liver as a target organ. Results of studies suggesting a role for inflammatory mediators in the hepatotoxicity caused by acetaminophen or ethanol are discussed. For several drugs, the evidence from animal models that concurrent inflammation increases injury is presented. In addition, the occurrence of adverse drug reactions in people with preexisting inflammatory diseases is considered. The special case of idiosyncratic drug reactions is discussed and the potential raised for development of animal models for this type of drug toxicity. The conclusion is that inflammatory factors should be considered as determinants of sensitivity to adverse drug reactions.

Antiretrovirals, Part II: Focus on Non-Protease Inhibitor Antiretrovirals (NRTIs, NNRTIs, and Fusion Inhibitors)

The second in a series reviewing the HIV/AIDS antiretroviral drugs. This review summarizes the non-protease inhibitor antiretrovirals: nucleoside and nucleotide analogue reverse transcriptase inhibitors (NRTIs), the nonnucleoside reverse transcriptase inhibitors (NNRTIs), and cell membrane fusion inhibitors. In an overview format for primary care physicians and psychiatrists, this review presents the mechanism of action, side effects, toxicities, and drug interactions of these agents.

Pharmacogenetics of antiretroviral therapy: genetic variation of response and toxicity

The application of a pharmacogenetic approach to antiretroviral drug therapy represents a significant challenge, as treatment involves multiple drugs and drug classes with the potential for significant variability in drug–host, as well as drug–drug, interactions. However, despite this inherent complexity, considerable gains have been made in understanding how genetic factors influence the efficacy and toxicity of HIV therapy. In this review the available evidence regarding genetic variation in drug disposition will be examined, including the potential for relatively polymorphic drug-metabolizing enzymes (e.g., cytochrome P450 isoforms) and drug transporters (e.g., P-glycoprotein) to influence the disposition of HIV protease inhibitor and non-nucleoside reverse transcriptase inhibitor drugs. In addition, the role of genetic variation in determining the immune response to drug-specific antigens will be considered as a potentially significant determinant of susceptibility to idiosyncratic drug reactions (e.g., major histocompatibility complex alleles associated with abacavir hypersensitivity). The current and potential clinical utility of pharmacogenetic testing in HIV management will also be emphasized.

HIV and hepatitis C virus co-infection

Since the decline in HIV-related morbidity and mortality after introduction of highly active antiretroviral therapy (HAART) in 1996, liver disease caused by chronic infection with hepatitis C virus (HCV) has become an increasingly important cause of morbidity and mortality among HIV-infected patients infected parenterally with HCV in more developed countries. A third of HIV-infected individuals in Europe and the USA have HCV co-infection. HIV accelerates HCV liver disease especially when HIV-associated immunodeficiency progresses. With the introduction of pegylated interferon in combination with ribavirin, greatly improved treatment options for patients with HIV and HCV co-infection have become available and have led to sustained virological response rates of up to 40%. Furthermore, recent cohort analyses have shown that immune reconstitution induced by HAART can improve the course of hepatitis C leading to a decline in liver-related mortality. However, patients with HCV co-infection are at increased risk of hepatotoxicity from HAART. Owing to the high rates of HIV and HCV co-infection worldwide, new improved treatment strategies and guidelines for the management of co-infection remain a major future goal.