This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Hematology, Subject name: Pharmacology
The anticoagulant activity of warfarin can be potentiated by all of the following except 
Select and explain. 
A. Aspirin, B. Disulfiram, C. Rifampin, D. Phenylbutazone
C: Rifampin
Answer: C: Rifampin 
Explanation: Rifampin induces the hepatic mixed function oxidases that metabolize warfarin. Platelet inhibitors, such as aspirin, increase the anticoagulant effect of warfarin. Phenylbutazone can transiently increase the level of free warfarin by displacing it from the plasma albumin binding site. Cimetidine inhibits warfarin metabolism and causes potentiation of the anticoagulant. Ref: SHARMA N SHARMA chapter 10 blood and blood products.