Increased plasma concentration w/ certain antifungals (e.g. miconazole, fluconazole). Protein-bound drugs (e.g. NSAIDs, other sulfonamides, oral anticoagulants, hydantoins), probenecid, MAOIs, and chloramphenicol may potentiate hypoglycaemic action of glipizide. Diminished therapeutic effect w/ thiazides, other diuretics, phenothiazines, thyroid agents, oestrogens, OC, phenytoin, nicotinic acid, sympathomimetics, Ca channel blockers, rifampicin and isoniazid. Concomitant use w/ beta-blockers may impair glucose tolerance, increase frequency or severity of hypoglycaemia and block hypoglycaemia-induced tachycardia. Decreased serum concentration w/ colesevelam.