The potential of drug-drug interaction between efavirenz and rifampicin is a major concern in the treatment of HIV and tuberculosis. The optimal efavirenz dosage is still unclear. Our randomized control trial study recently reported the similar efavirenz level between efavirenz 600 and 800 mg/day in HIV-infected patients receiving rifampicin. We report the similar virological and immunological outcomes at 48 weeks between the two groups. Efavirenz 600 mg/day should be sufficient for concurrent use with rifamipicin.
