This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Pharmacology, Subject name: Pharmacology
All the following drugs are inducers of cytochrome P450 enzymes except - 
Select and explain. 
A. Ritonavir, B. Chloral hydrate, C. Isoniazid, D. Ketoconazole
D: Ketoconazole
Answer: D: Ketoconazole 
Explanation: Ans. is 'd' i.e., Ketoconazole Drugs that induce microsomal enzymes* Phenobarbitone* Carbamezepine* Phenytoin* Omeprazole* Rifampin* Clofibrate* Glucocorticoids* Meprobamate* Isoniazid* Ritonavir* Chloral hydrate* Glutethimide* Phenylbutazone* Chronic alcohol intake* Griseofulvin* Cigarette smoking* DDT* Cyclophosphamide Drugs that inhibit drug metabolizing enzymes* Allopurinol* Diltiazem* Omeprazole* Amiodarone* Erythromycin* Propoxyphene* Clarithromycin* Isoniazid* Chloramphenicol* Cimetidine* Phenylbutazone* Quinidine* Ketoconazole* Metronidazole* Itraconazole* Disulfiram* Ciprofloxacin* Verapamil* Sulfonamides* MAO inhibitors