RIFAMPACIN: Powerful enzyme inducer of the Hepatic Cytochrome P450 system. It increasesmetabolism of many drugs and as a consequence, can make them less effective, or even ineffective in some cases, by decreasing their levels in the plasma. Rifampicin can induce the metabolism of Indinavir and can result in therapeutic failure. Therfore rifampicin is avoided in the above patient. ISOENZYMES INDUCED BY RIFAMPACIN: CYP2C9 CYP2C19 CYP3A4 CYP1A2