This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pharmacology, Subject name: Pharmacology
Which of the following is NOT a prodrug 
Select and explain. 
A. Enalapril, B. Sulphasalazine, C. Imipramine, D. Cyclophosphamide
C: Imipramine
Answer: C: Imipramine 
Explanation: Activation of inactive drug:- Few drugs are inactive as such and need conversion in the body to one or more active metabolites. Such a drug is called a prodrug. The prodrug may offer advantages over the active form in being more stable, having better bioavailability, less side effects and toxicity. Ref:- kd tripathi; pg num:-22,23