Abstract
Pharmacokinetic interactions between rifampicin and nonnucleoside analogue reverse transcriptase inhibitors (NNRTIs) pose challenges in the treatment of TB/HIV coinfection. We describe NNRTI plasma concentrations (PC) and treatment outcomes in TB/HIV coinfected patients receiving rifampicin and NNRTIs concomitantly. Single center prospective data were collected on all TB/HIV-coinfected patients who received concomitant NNRTI and rifampicin between 2001 and 2005. Of 103 TB/HIV coinfected patients, 26 received concomitant rifampicin with efavirenz (EFV) and 17 with nevirapine (NVP). NNRTIs were commenced after rifampicin in 18/26 (69%) and 7/17 (41%) subjects treated with EFV and NVP, respectively. Of these 88% completed antituberculosis therapy. There were two (5%) deaths, both due to lymphoproliferative malignancy. Three (7%) patients transferred care or discontinued therapy. Of subjects 83% had normal liver function tests (LFTs) and 11% had Grade 1–2 and 6% Grade 3–4 LFT abnormalities during concomitant therapy. PCs were measured in 31 patients. The first PCs were within the therapeutic range in 5/7 on NVP 200 mg bd, 2/4 on NVP 300 mg bd, 3/7 EFV 600 mg od, and 7/13 on EFV 800 mg od. PCs were subtherapeutic in 4/11 (36%) and 3/20 (20%) subjects on NVP and EFV, respectively. No virological rebounds were observed. Of subjects receiving concomitant NVP or EFV with rifampicin, 64% and 80%, respectively, had therapeutic NNRTI PCs. Subtherapeutic PCs were not associated with virological failure. Good clinical outcomes and a low incidence of hepatotoxicity were observed.