<prompt> Rifampicin is a powerful enzyme inducer. It is most likely to induce the metabolism of which of the following anti-retroviral drugs?TenofovirNevirapineAbacavirZidovudine  <response>: Rifampicin is a microsomal enzyme inducer - increases several CYP450 isoenzymes, including CYP3A4 , CYP2D6, CYP1A2 and CYP2C subfamily. It thus enhances its own metabolism as well as that of many drugs including warfarin, oral contraceptives, coicosteroids, sulfonylureas, HIV protease inhibitors, non-nucleoside reverse transcriptase inhibitors NNls, theophylline, metoprolol, fluconazole, ketoconazole, clarithromycin, phenytoin, etc. Among given options, Nevirapine NNI is the best answer. 