Prolonged activity w/ 6-mercaptopurine or azathioprine. Prolonged hypoglycaemic activity w/ chlorpropamide. Increased effect of anticoagulants. Enhanced bone marrow suppression w/ cyclophosphamide & other cytotoxic agents. Enhanced toxicity of ciclosporin. Increased levels of theophylline due to inhibition of metabolism. Increased plasma t½
of vidarabine. Frequent skin rash w/ ampicillin or amoxicillin. Decreased therapeutic activity of allopurinol w/ uricosuric agents eg probenecid. Enhanced action of salicylates. Fe supplements, phenytoin, ampicillin, amoxicillin.