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
Warfarin therapy is prolonged by all except: 
Select and explain. 
A. Rifampicin, B. Amoxicillin, C. Erythromycin, D. Tetracycline
A: Rifampicin
Answer: A: Rifampicin 
Explanation: Barbiturates (but not benzodiazepines), carbamazepine, rifampicin and griseofulvin induce the metabolism of warfarin.The dose of anticoagulant determined during therapy with these drugs would be higher: if the same is continued after withdrawing the inducer- marked hypoprothrombinemia can occur causing fatal bleeding.
Reference: Essentials of Medical Pharmacology Eighth Edition KD TRIPATHI page no 670