This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pharmacology
CYP-450 inducers are - 
Select and explain. 
A. Cimetidine, B. Ketoconazole, C. Phenobarbitone, D. All
C: Phenobarbitone
Answer: C: Phenobarbitone 
Explanation: Ans. is 'c' i.e., Phenobarbitone Drugs that induce microsomal enzymes o Phenobarbitone o Rifampin o Isoniazid o Phenylbutazone o DDT o Carbamezepine o Clofibrate o Ritonavir o Chronic alcohol intake o Cyclophosphamide o Phenytoin o Glucocoicoids o Chloral hydrate o Griseofulvin o Omeprazole o Meprobamate o Glutethimide o Cigarette smoking Remember o All Barbiturates are enzyme inducers except secobarbital, which inhibits the enzyme. o Acutely, ritonavir is an inhibitor, while with chronic (repeated) administration it acts as an inducer.