Therapeutic monitoring of plasma level of drug is done when using all of the following drugs except: (A) Warfarin, (B) Gentamicin, (C) Cyclosporine, (D) Phenytoin
Answer is A. 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).