<prompt> Which of the following drugs is an inhibitor of cytochrome p450 enzymes?KetoconazoleRifampicinPhenytoinPhenobarbitone  <response>: Ans. A KetoconazoleRef: KDT 8the p30Ketoconazole is a powerful microsomal enzyme inhibitor whereas rifampicin, phenobarbitone and phenytoin are enzyme inducers. 