Concomitant use w/ 6-mercaptopurine, azathioprine, vidarabine, salicylate & other uricosuric agents, chlorpropamide, coumarin anticoagulants, phenytoin, theophylline, ampicillin/amoxicillin, cyclophosphamide, doxorubicin, bleomycin, procarbazine, mechlorethamine, cyclosporin, didanosine, diuretics, ACE inhibitor.