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
Administration of which of the following drug requires monitoring: 
Select and explain. 
A. Lithium, B. Haloperidol, C. Diazepam, D. Acetazolamide
A: Lithium
Answer: A: Lithium 
Explanation: Ans. A: Lithium Therapeutic drug monitoring is the measurement of medication levels in blood. Its main focus is on drugs with a narrow therapeutic index, i.e. drugs that can easily be under- or overdosed. Examples of drugs analysed by therapeutic drug monitoring: Aminoglycoside antibiotics (gentamicin) Antiepileptics (such as carbamazepine, phenytoin and valproic acid) Mood stabilisers, especially lithium citrate Antipsychotics (such as pimozide and clozapine) Theophylline Digoxin Antiarrhythmics