This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Autacoids, Subject name: Pharmacology
Which of the following describes the action of allopurinol 
Select and explain. 
A. Inhibits metabolism of purines to uric acid, B. Interferes with cytokine production, C. Inhibits uric acid reabsorption, D. Inhibits prostaglandin biosynthesis
A: Inhibits metabolism of purines to uric acid
Answer: A: Inhibits metabolism of purines to uric acid 
Explanation: URIC ACID SYNTHESIS INHIBITORS Allopurinol:- Mech of action:- Allopurinol is a sho-acting (t 1/2 2 hrs) competitive inhibitor of xanthine oxidase, but its major metabolite alloxanthine (oxypurine) is a long-acting (t 1/2 24 hrs) and noncompetitive inhibitor--primarily responsible for uric acid synthesis inhibition in vivo. At high concentrations, allopurinol also becomes noncompetitive inhibitor. During allopurinol administration, plasma concen tration of uric acid is reduced and that of hypoxanthine and xanthine is somewhat increased. Because of raised levels of xanthine and hypoxanthine, some feedback inhibition of de novo purine synthesis and reutilization of metabolically derived purine also occurs. Ref:- kd tripathi; pg num:-216