This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Pharmacology
[{'content': 'Therapeutic drug monitoring is essential for the following drug? \nSelect and explain. \nA. Diazepam, B. Pencillin, C. Cyclosporine, D. Metformin', 'role': 'user'}, {'content': 'Answer: C \nExplanation: TDM is required for drugs with narrow therapeutic range like1. Immunosuppressants like cyclosporin and tacrolimus,2. Lithium,3. Antiepileptic drugs like phenytoin, Phenobarbitone, Carbamazepine etc.Ref: KD Tripathi 7th ed.Pg 34', 'role': 'assistant'}]