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
[{'content': 'Therapeutic monitoring of plasma level of drug is done when using all of the following drugs except \nSelect and explain. \nA. Warfarin, B. Gentamicin, C. Cyclosporine, D. Phenytoin', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (A) Warfarin(Ref: KDT 8th/e p42)Therapeutic drug monitoring is not required for oral anticoagulants like warfarin. The effect of warfarin is monitored by measuring prothrombin time or INR (International Normalized Ratio).', 'role': 'assistant'}]