Amlodipine has been safely administered with thiazide diuretics, β-adrenoceptor blocking drugs, angiotensin-converting enzyme inhibitor, long-acting nitrates, sublingual glyceryl nitrate, nonsteroidal anti-inflammatory drugs, antibiotics and oral hypoglycaemic agents. Co-administration of cimetidine did not alter the pharmacokinetics of amlodipine. In vitro data from studies with human plasma indicate that amlodipine has no effect on protein-binding of digoxin, phenytoin, warfarin or indomethacin.