Introduction: Co-management of tuberculosis (TB) and HIV is complicated by pharmacologic drug
interactions between rifampicin (RMP) and certain classes of antiretroviral agents. The NNRTIs
Nevirapine (NVP) or Efavirenz (EFV), used to HIV infection, are known to induce the CYP 450
enzyme system. Thus when RMP is co-administered along with NVP or EFV, the bioavailability of
RMP could be lowered leading to drug resistance and treatment failure.
Objectives: To study the steady state pharmacokinetics of RMP in HIV and HIV-TB patients
receiving antiretroviral regimens containing NVP or EFV respectively.
Methods: The study population comprised of HIV and HIV-TB patients undergoing antiretroviral
treatment with NVP and EFV containing regimens respectively. These patients were also receiving
concomitant RMP. Rifampicin was estimated by HPLC in blood collected at different time points
after drug administration. The pharmacokinetic variables of RMP were calculated using WinNonlin
software.
Results & Conclusions: Co-administration of NVP or EFV did not alter the pharmacokinetics of
RMP in HIV and HIV-TB patients, suggesting that the dose of RMP need not be altered during
antiretroviral treatment with NVP or EFV
