This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Ulcer, Subject name: Pharmacology
Cimetidine inhibits the metabolism of all of the following drugs except. 
Select and explain. 
A. Phenytoin, B. Warfarin, C. Ketoconazole, D. Diazepam
C: Ketoconazole
Answer: C: Ketoconazole 
Explanation: Ans. (C) Ketoconazole(Ref: KDT 8th/e p698)Cimetidine is a potent inhibitor of microsomal enzymes. It prolongs the half lives of warfarin, theophylline, phenytoin, oral hypoglycemic agents, alcohol and benzodiazepines.