The antiretroviral efficacy of highly active antiretroviral therapy and plasma nevirapine concentrations in HIV-TB co-infected Indian patients receiving rifampicin based antituberculosis treatment

BACKGROUND: Rifampicin reduces the plasma concentrations of nevirapine in human immunodeficiency virus (HIV) and tuberculosis (TB) co-infected patients, who are administered these drugs concomitantly. We conducted a prospective interventional study to assess the efficacy of nevirapine-containing highly active antiretroviral treatment (HAART) when co-administered with rifampicin-containing antituberculosis treatment (ATT) and also measured plasma nevirapine concentrations in patients receiving such a nevirapine-containing HAART regimen. METHODS: 63 cases included antiretroviral treatment naïve HIV-TB co-infected patients with CD4 counts less than 200 cells/mm(3 )started on rifampicin-containing ATT followed by nevirapine-containing HAART. In control group we included 51 HIV patients without tuberculosis and on nevirapine-containing HAART. They were assessed for clinical and immunological response at the end of 24 and 48 weeks. Plasma nevirapine concentrations were measured at days 14, 28, 42 and 180 of starting HAART. RESULTS: 97 out of 114 (85.1%) patients were alive at the end of 48 weeks. The CD4 cell count showed a mean increase of 108 vs.113 cells/mm3 (p=0.83) at 24 weeks of HAART in cases and controls respectively. Overall, 58.73% patients in cases had viral loads of less than 400 copies/ml at the end of 48 weeks. The mean (± SD) Nevirapine concentrations of cases and control at 14, 28, 42 and 180 days were 2.19 ± 1.49 vs. 3.27 ± 4.95 (p = 0.10), 2.78 ± 1.60 vs. 3.67 ± 3.59 (p = 0.08), 3.06 ± 3.32 vs. 4.04 ± 2.55 (p = 0.10) respectively and 3.04 μg/ml (in cases). CONCLUSIONS: Good immunological and clinical response can be obtained in HIV-TB co-infected patients receiving rifampicin and nevirapine concomitantly despite somewhat lower nevirapine trough concentrations. This suggests that rifampicin-containing ATT may be co administered in resource limited setting with nevirapine-containing HAART regimen without substantial reduction in antiretroviral effectiveness. Larger sample sized studies and longer follow-up are required to identify populations of individuals where the reduction in nevirapine concentration may result in lower ART response or shorter response duration.