Potentiation of effects when used w/ insulin & other antidiabetics, ACE inhibitors, allopurinol, anabolic steroids & male sex hormones, chloramphenicol, coumarin derivatives, cyclophosphamide, disopyramide, fenfluramine, fenylramidol, fibrates, fluoxetine, guanethidine, ifosfamide, MAOIs, miconazole, p-amino salicylic acid, pentoxifylline, high dose quinolones, salicylates, sulfinpyrazones, sulfonamides, tetracyclines, tritoqualine, trofosfamide. Weakening of the blood glucose lowering effects when used w/ acetazoliamide, barbiturates, corticosteroids, diazoxide, diuretics, epinephrine & other sympathomimetics, glucagon, laxatives (other protracted use), nicotinic acid (high dose), oestrogens & progesterons, phenothiazines, phenytoin, rifampicin, thyroid hormones, β-blockers decrease glucose tolerance.