Metformin: Increased blood glucose levels w/ glucocorticoids, β
2-agonists, diuretics, phenothiazines, thyroid hormones, oestrogens, OCs, hormone replacement therapy, phenytoin, nicotinic acid, Ca channel blockers, INH & tetracosactide. Increased plasma levels w/ furosemide & nifedipine. Increased C
max & AUC w/ cimetidine. Decreased blood glucose w/ β-blockers & ACE inhibitors. Increased hypoglycaemic effect w/ MAOIs & oral antidiabetics. Potentiated hypoglycaemic effect w/ alcohol. Increased or reduced hypoglycaemic effect w/ H
2-antagonists, clonidine & reserpine, quinolones. Increased risk of lactic acidosis w/ diuretics, iodinated contrast media, alcohol, NSAIDs, ACE inhibitors, angiotensin II receptor antagonists. Lowered plasma levels of furosemide. Reduced effect of phenprocoumon. Less perceptible warning signs of hypoglycaemia w/ sympatholytics.