Abacavir-induced hepatotoxicity: a report of two cases

Hepatotoxicity of contemporary antiretroviral drugs

PURPOSE OF REVIEW

To date, more than 30 antiretroviral drugs have been approved by the Food and Drug Administration for the treatment of HIV infection. As new drugs with better efficacy and safety profile become available for clinical practice, older drugs are either withdrawn from the market or become no longer actively prescribed. We review hepatotoxicity associated with contemporary antiretroviral drugs, with emphasis on data from the past 3 years.

RECENT FINDINGS

Although less robust data exists for side effects of contemporary antiretroviral medications recently approved for the management of HIV (i.e., doravirine, ibalizumab, fostemsavir, cabotegravir), the risks of substantial hepatotoxicity appears to be minimal with these agents.

SUMMARY

Although newer antiretroviral drugs are better tolerated than their earlier counterparts, they are not completely devoid of adverse drug reactions, including hepatotoxicity. Monitoring patients on antiretroviral therapy for treatment-emergent liver injury should continue to be part of routine clinical care.

Hepatotoxicity of Contemporary Antiretroviral Drugs: A Review and Evaluation of Published Clinical Data

Contemporary antiretroviral agents afford enhanced potency and safety for patients living with HIV. Newer antiretroviral drugs are often better tolerated than those initially approved in the early stages of the HIV epidemic. While the safety profile has improved, adverse drug reactions still occur. We have segregated the antiretroviral agents used in contemporary practice into class groupings based on their mechanism of antiviral activity (non-nucleoside reverse transcriptase inhibitors, nucleoside reverse transcriptase inhibitors, integrase inhibitors, protease inhibitors, and entry inhibitors) while providing a review and discussion of the hepatoxicity seen in the most relevant clinical literature published to date. Clinical literature for individual agents is discussed and agent comparisons afforded within each group in tabular format. Our review will provide a summative overview of the incidence and medications associated with hepatic adverse reactions linked to the use of contemporary antiretroviral drugs.

Severe hepatotoxicity induced by efavirenz in a treatment-naïve, low body mass index HIV-infected, female patient with no hepatitis and other virus co-infections

Combined antiretroviral therapy (cART) consisting of two nucleoside reverse transcriptase inhibitors (NRTIs) and one non-nucleoside reverse transcriptase inhibitor (NNRTI), such as efavirenz, is still the first-line treatment in resource-limited settings. However, efavirenz has shown strong prominence of disadvantages with variance in plasma concentration and central nervous side effects. Our study presents HIV infected, drug naïve, female patient with relatively low BMI, CYP2B6 516G>T (rs3745274) genotype with high efavirenz plasma concentration. In this case report, the patient was admitted at the hospital 6 months after cART initiation with drug-induced severe hepatotoxicity. Furthermore, pathophysiological findings proved confluent parenchymal necrosis after aspiration liver biopsy, with mild to moderate inflammation in portal tracts with focal interface hepatitis. All other possible causes were excluded. Thus, we conclude that efavirenz has a potential harmful effect in patients with low BMI, specific genotyping and interindividual pharmacokinetics affecting high plasma concentration.

Abacavir/Dolutegravir/Lamivudine (Triumeq)-Induced Liver Toxicity in a Human Immunodeficiency Virus-Infected Patient

Drug-induced liver injury related to Triumeq (abacavir/lamivudine/dolutegravir) has not been reported in clinical trials. We report a case of hepatotoxicity related to Triumeq exposure in a human immunodeficiency virus-infected patient. Clinicians should remain aware of the risk for acute and late-onset hepatitis with these agents. Close monitoring is recommended.

Abacavir-induced liver toxicity

Abacavir-induced liver toxicity is a rare event almost exclusively occurring in HLA B*5701-positive patients. Herein, we report one case of abnormal liver function tests occurring in a young HLA B*5701-negative woman on a stable nevirapine-based regimen with no history of liver problems or alcohol abuse after switching to abacavir from tenofovir. We also investigated the reasons for abacavir discontinuation in a cohort of patients treated with abacavir-lamivudine-nevirapine.

The purine analogues abacavir and didanosine increase acetaminophen-induced hepatotoxicity by enhancing mitochondrial dysfunction

BACKGROUND

NRTIs are essential components of HIV therapy with well-documented, long-term mitochondrial toxicity in hepatic cells, but whose acute effects on mitochondria are unclear. As acetaminophen-induced hepatotoxicity also involves mitochondrial interference, we hypothesized that it would be exacerbated in the context of ART.

METHODS

We evaluated the acute effects of clinically relevant concentrations of the most widely used NRTIs, alone or combined with acetaminophen, on mitochondrial function and cellular viability.

RESULTS

The purine analogues abacavir and didanosine produced an immediate and concentration-dependent inhibition of oxygen consumption and complex I and III activity. This inhibition was accompanied by an undermining of mitochondrial function, with increased production of reactive oxygen species and reduction of mitochondrial membrane potential and intracellular ATP levels. However, this interference did not compromise cell survival. Co-administration with concentrations of acetaminophen below those considered hepatotoxic exacerbated the deleterious effects of both compounds on mitochondrial function and compromised cellular viability, showing a clear correlation with diminished glutathione levels.

CONCLUSIONS

The simultaneous presence of purine analogues and low concentrations of acetaminophen significantly potentiates mitochondrial dysfunction, increasing the risk of liver injury. This new mechanism is relevant given the liver's susceptibility to mitochondrial dysfunction-related toxicity and the tendency of the HIV infection to increase oxidative stress.

Abacavir-induced fulminant hepatic failure in a HIV/HCV co-infected patient

Abacavir hypersensitivity is a rare, yet significant adverse reaction that results in a spectrum of physical and laboratory abnormalities, and has been postulated to stem from a variety of aetiological factors. The major histocompatibility complex haplotype human leucocyte antigen (HLA)-B5701 is a significant risk factor in development of hypersensitivity reactions, yet only 55% of HLA-B5701+ individuals develop such reactions, suggesting a multifactorial aetiology. Nevertheless, prospective screening and avoidance of abacavir in these patients has limited adverse events. Within this spectrum of adverse events, abacavir-induced liver toxicity is exceedingly rare and reported events have ranged from mild elevations of aminotransferases to fulminant hepatic failure. We report the case of a 50-year-old Caucasian woman with a history significant for HIV, hepatitis C virus and a HLA-B5701+ status, transferred to our emergency department in a hypotensive state and found to have acute liver failure, acute renal failure and significant rhabdomyolysis following a change of highly active antiretroviral therapy regimen.

Latest advances in predicting DILI in human subjects: focus on biomarkers

INTRODUCTION

The quest for a biomarker that would reliably identify patients at risk of developing acute drug-induced liver injury (DILI) to a specific agent or class of agents before it occurs, has been underway for years. Historical host factors for DILI, such as older age and female gender, are not considered sufficient to truly predict an individual's inherent risk of DILI. In vitro and animal-based biomarker discoveries, in many instances, have not been considered accurate enough for drug development in human subjects nor for use in clinical practice.

AREAS COVERED

In order to assess the current state of biomarkers to predict idiosyncratic human DILI, the authors utilized the PubMed literature search tool to identify research reports dealing with clinical DILI biomarkers covering the period of 2010 through to June 2012. Studies involving pharmacogenetic, proteomic and toxicogenomic analyses are preferentially reviewed.

EXPERT OPINION

Although acute DILI has been linked to specific genetic associations (e.g., flucloxacillin and HLA-B*5701; and certain polymorphisms seen with anti-TB agent DILI), such predictors have been able to identify only some patients at risk for only a limited number of drugs. Proteomic-based biomarkers from stored sera in the US DILI Network, such as apolipoprotein E, have been identified as potential candidates, but require further study. As it currently stands, the quest for a widely applicable, validated DILI biomarker remains an ongoing clinical challenge.