This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Pharmacology
Oral contraceptive failure occurs with 
Select and explain. 
A. Cimetidine, B. Rifampicin, C. Morphine, D. Ethanol
B: Rifampicin
Answer: B: Rifampicin 
Explanation: (Rifampicin) (1628 - Man & Gillmann) (741-KDT 6th)CONTRACEPTION FAILURE - May occure if the following drugs are used concurrently(a) Enzyme inducers - Phenytoin, Phenobarbitone, Primidone, Carbamazepine, Rifampicin, Rifabutin(b) Suppression of intestinal micro flora - Tetracyclines Ampicilline Doxycycilline