Therapeutic monitoring of plasma level of drug is done when using all of the following drugs except
Warfarin
Gentamicin
Cyclosporine
Phenytoin
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).
General Pharmacology