Using rifampin-based therapy alongside a triple antiretroviral regimen that contains drugs from the NNRTI class (either nevirapine or efavirenz) does not result in a poorer response to treatment or greater toxicity, South African researchers reported last week at the Third International AIDS Society Conference on HIV Treatment and Pathogenesis in Rio de Janeiro, Brazil.
Concern persists over the effect of interactions between rifampin and nevirapine or efavirenz, and the possibility that rifampin will reduce blood levels of the NNRTI, leading to sub-optimal anti-HIV treatment and drug resistance. No long-term randomised study has yet reported on the effects of rifampin, and the South African study is the first substantial review of the clinical outcomes of patients in a resource-limited setting taking both regimens at the same time.
South African researchers set out to compare outcomes of patients with and without tuberculosis (TB) receiving rifampin-based treatment who commenced NNRTI-containing ART regimens. They looked at outcomes in the Medecins sans Frontieres Khayelitsha community cohort, which provides prospective follow-up.
The study reviewed 1731 patients with a median CD4 cell count of 76 cells/mm3 at baseline and high viral load (median 5.4 log10 copies/ml, 250,000 copies/ml). Twenty-five per cent were receiving TB treatment at the time they began antiretroviral therapy (ART), and the vast majority had completed at least two months of TB treatment by this point (45% >2 months, 34%>4 months).
Initial regimens in the cohort were fairly evenly divided between nevirapine and efavirenz-containing regimens (EFV 808, NVP 918).
After three months of antiretroviral treatment, individuals receiving concomitant TB treatment were significantly less likely to have viral load below 400 copies/ml, but this difference was no longer apparent at month six (8.3% vs 13% at month 3, p=0.045; 8.6% vs 9.1% at month 6, p=0.91).
There was no difference in survival or immunologic outcomes at month six, nor any evidence of increased mortality due to immune reconstitution syndrome or advanced HIV disease in the TB treatment group.
Although a trend towards more treatment switches due to hepatotoxicity was observed in the nevirapine/TB treatment group, this was not associated with concomitant rifampin treatment (8% vs 4%, p=0.849).
Van Cutsem G et al. TB/HIV coinfected patients on rifampicin-containing treatment have equivalent ART treatment outcomes and concurrent use of nevirapine is not associated with increased hepatotoxicity. Third International AIDS Society Conference on HIV Pathogenesis and Treatment, Rio de Janeiro, Brazil, abstract WePp0303, 2005.