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
Therapeutic drug monitoring is advised in allexcept 
Select and explain. 
A. Metformin, B. Phenytoin, C. Tacrolimus, D. Cyclosporine
A: Metformin
Answer: A: Metformin 
Explanation: Ans. is 'a' i.e., Metformin o Drugs whose response is easily measurable eg. hypoglycaemics (metformin), antihypeensive, diuretics, oral anticoagulants and general anaesthetics, monitoring of plasma conc. is of no value.