Allopurinol potentiates the action of
Allopurinol inhibits xanthine oxidase, which metabolizes 6 MP and azathioprine, so dose of 6-mp is reduced to 1/4 to 1/2 if refuse along with you allopurinol Refer kDT 6/e p209
Coicosteroids
Probenecid
6-mercaptopurine
Ampicillin
Autacoids