Reduced glycaemic control w/ diuretics, barbiturates, phenytoin, rifampicin, corticosteroids, estrogens, estroprogestin & pure progestogens. Potentiated hypoglycaemic action by salicylates, phenylbutazone, sulfonamides, β-blockers, clofibric acid, vit K antagonist, allopurinol, theophylline, caffeine & MAOIs. Gliclazide: Concomitant use w/ miconazole, perhexiline or cimetidine. Metformin: Decreased oral bioavailability w/ acarbose & guar gum.