Which of the following drugs is an inhibitor of cytochrome p450 enzymes ?: (A) Ketoconazole, (B) Rifampicin, (C) Phenytoin, (D) Phenobarbitone
Answer is A. - Cytochrome p450 enzymes are microsomal enzymes (present on smooth endoplasmic reticulum).
- Of the given options, only Ketoconazole is a microsomal enzyme inhibitor. Rest all are enzyme inducers.