This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: NSAIDs, Gout and Rheumatoid Ahritis, Subject name: Pharmacology
Which of the following disease modifying anti- rheumatoid drugs is a prodrug? 
Select and explain. 
A. Etanercept, B. Nimesulide, C. Sulfasalazine, D. Colchicine
C: Sulfasalazine
Answer: C: Sulfasalazine 
Explanation: - Sulfasalazine is a pro-drug. - It dissociates in the colon to produce 5-ASA (MESELAMINE) and sulfapyridine. - 5-ASA is the active moiety in treatment of ulcerative colitis whereas sulfapyridine is used to treat rheumatoid ahritis.