<prompt> Allopurinol potentiates the action ofCoicosteroidsProbenecid6-mercaptopurineAmpicillin  <response>: Allopurinol inhibits xanthine oxidase, which metabolizes 6 MP and azathioprine, so dose of 6-mp is reduced to 14 to 12 if refuse along with you allopurinol Refer kDT 6e p209 