HIV infection, antiretroviral therapy, and hepatic function. Emerging epidemiological, pathogenetic, and clinical issues, and their consequences on disease management

Prospective, Open-Label Comparative Study of Liver Toxicity in an Unselected Population of HIV-Infected Patients Treated for the First Time with Efavirenz or Nevirapine

OBJECTIVE

To compare the two nonnucleoside reverse transcriptase inhibitors (NNRTIs) when first introduced in an antiretroviral regimen, a prospective open-label assessment of the frequency, severity, risk factors, and outcome of hepatotoxicity was performed.

METHOD

Liver enzymes were followed-up during 18 months in patients who received efavirenz (EFV; 324 patients) or nevirapine (NVP; 299).

RESULTS

The two study groups were comparable, except for the lower baseline CD4+ count found in the EFV group. No differences were found when considering the type and duration of eventual prior anti-HIV therapy; frequency and length of protease inhibitors, methadone, or anti-tubercular drug use; HCV-HBV co-infection; other hepatobiliary disorders; and alcohol-drug abuse. The frequency of overall and first-month drug interruption proved similar in the two study groups. A hepatotoxicity characterized by at least a 2-fold increase of transaminases versus baseline was significantly linked with NVP, and the number of patients showing hepatotoxicity tended to a reduction in the EFV group. Also the time to peak transaminase alterations was shorter in the NVP group. All significant differences regarding liver-pancreatic toxicities were controlled per eventual baseline hepatobiliary-pancreatic diseases, HIV stage, and concurrent drug therapies.

DISCUSSION

Hepatotoxicity is a significant concern in the setting of antiretroviral-treated HIV disease. NVP-based HAART may be more hepatotoxic than EFV-based HAART, and a role is played by chronic liver disorders. Although concurrent hepatobiliary disorders and the possible hepatotoxicity of antiretrovirals do not represent contraindications to nonnucleoside inhibitor use, strict monitoring is recommended.

Nevirapine versus efavirenz in 742 patients: no link of liver toxicity with female sex, and a baseline CD4 cell count greater than 250 cells/microl

Recent studies have reported increased nevirapine hepatotoxicity in female patients with CD4 lymphocyte counts greater than 250 cells/microl (especially pregnant women). However, our open-label comparison of 742 patients treated with either nevirapine or efavirenz-based HAART as naive patients, experienced subjects, or patients on salvage therapy, found no increased hepatotoxicity in nevirapine-treated subjects, in particular with regard to both sex (females versus males) and T-cell-mediated immunodeficiency (CD4 cell counts above versus below 250 cells/microl).

Efavirenz Versus Nevirapine in Current Clinical Practice: A Prospective, Open-Label Observational Study

An open-label, observational, prospective 18-month survey was conducted to compare the efficacy and tolerability of the 2 available nonnucleoside reverse transcriptase inhibitors (NNRTIs) in all possible indications of current clinical practice. A broad range of clinical and laboratory variables accounting for drug efficacy and tolerability (with special emphasis on metabolic and hepatic toxicity) were measured in 287 evaluable patients treated with efavirenz, compared with 258 subjects taking nevirapine for 18 months. A separate efficacy analysis was performed in 154 antiretroviral-naive subjects, 298 patients experienced with 2-7 prior anti-HIV lines who abandoned protease inhibitors (PIs), and 103 subjects entering a salvage regimen containing at least 4 drugs, including PIs. Antiretroviral-naive patients experienced greater efavirenz activity at 3-12 months (maximum HIV RNA drop =-2.4 log(10) copies/mL), associated with a significantly higher rate of complete viral suppression, while immunologic results proved significant only after 6-9 months. When assessing experienced patients and those on rescue regimens, a similar and progressively blunted laboratory response was achieved, on the ground of a worse baseline virologic and immunologic profile, and duration of prior anti-HIV therapy. Both first-month (4.2 and 4.3% for efavirenz and nevirapine, respectively) and overall discontinuation rates (11.5 and 12%, respectively) proved similar, but a profound difference emerged as to the different spectrum of untoward events: central nervous system (CNS) disturbances, persisting metabolic abnormalities, and possibly gynecomastia and laboratory pancreatic abnormalities for efavirenz vs. immediate allergy and increased hepatotoxicity (regardless of chronic infection with hepatitis B or C virus and methadone use) for nevirapine. A limited virologic and immunologic advantage of efavirenz was observed in the first 12-month assessment of antiretroviral-naive patients, whereas all other examined situations did not disclose relevant efficacy differences between efavirenz and nevirapine throughout the 18-month comparison. Although the short- and long-term toxicity and withdrawal rates of the 2 drugs were comparable, the different pathways prompting allergic, metabolic, liver, and CNS disturbances observed with NNRTIs deserve careful investigation, to prevent toxicity of these relevant antiretroviral compounds.

HIV infection and advanced age emerging epidemiological, clinical, and management issues

While the mean age of HIV/AIDS patients at first diagnosis is progressively rising, no updated epidemiological estimates, controlled clinical data, and randomized therapeutic trials, are available regarding clinical and laboratory response to antiretroviral therapy, safety of anti-HIV compounds and their associations, potential drug-drug interactions, short- and long-term toxicity, consequences on underlying disorders, or interactions with concomitant pharmacological regimens, in the elderly. The life expectancy of HIV-infected persons treated with highly active antiretroviral therapy (HAART) now approximates that of general population matched for age, while also AIDS definition itself has lost most of its epidemiological and clinical significance, thanks to the immunoreconstitution resulting from the large-scale use of potent HAART regimens. The increased survival of HIV-infected patients, the late recognition of other subjects with missed or delayed diagnosis are responsible for a further expected rise of mean age of HIV-infected individuals, so that the patient population aged 60-70 years or more is expected to increase in coming years. Unfortunately, the majority of therapeutic trials involving antiretroviral therapy, as well as antimicrobial chemoprophylaxis for AIDS-related opportunistic complications, have advanced age and/or concurrent end-organ disorders among main exclusion criteria, or the design of these studies does not allow to extrapolate data regarding older patients, compared with younger ones. The very limited data presently available seem to demonstrate that HAART has a virological efficacy in the elderly comparable with that of younger adults, but immunological recovery is often slower and blunted, although several studies clearly demonstrated that thymic function is preserved until late adult age. When facing an HIV-infected patient with advanced age, health care givers have to pay careful attention to eventual end-organ disorders, all possible pharmacological interactions, overlapping toxicity due to concurrent drug administration. All these issues may significantly interfere with HAART activity, patient's adherence to prescribed medications, and frequency and severity of untoward effects. The guidelines of antiretroviral therapy and those of treatment and prophylaxis of AIDS-related diseases deserve appropriate updates, paralleling the increasing mean age of HIV-infected population. Moreover, epidemiological figures need an increased focus on older age, while clinical trials specifically targeting on the elderly population are mandatory to have reliable data on all aspects of HAART administration in advanced age.