Active metabolite of azathioprine ?

Ans. is 'c' i.e., 6-mercaptopurine Azathioprine It is an analogue of mercaptopurine. It selectively affects T cells - cellular immunity is predominantly affected. It selectively affects defferentiation and formation of T cells. Azathioprine is conveed to active metabolite 6-mercaptopurine. It can inhibit the synthesis of both DNA & RNA. Azathioprine and 6-MP are metabolize by xanthine oxidase -dose should be reduced if allopurinol (a xanthine oxidase inhibitor) is used concurrently. The most impoant action of azathioprine is prevention of renal and other graft rejection.