Pharmacology: Pharmacodynamics: Amlodipine is a calcium channel blocker (slow channel blockers or calcium antagonist) which inhibits the movement of calcium ions across cardiac and vascular smooth muscle. The effects on the cardiovascular system include depression of mechanical contraction of myocardial and smooth muscle as well as depression of both impulse formation and conduction velocity. Amlodipine dilates the coronary arteries and arterioles in normal and ischemic regions and inhibits coronary artery spasm and vasospastic (Prinzmetal's or variant) angina. This reduces myocardial energy consumption and oxygen requirements and probably accounts for efficacy in chronic stable angina. The drug reduces arterial blood pressure at rest and with exercise by dilating peripheral arterioles and reducing total peripheral resistance (afterload).
Pharmacokinetics: Absorption/Distribution: Amlodipine is slowly and almost completely absorbed from the gastrointestinal tract, absorption not affected by food. Highly protein bound. Absolute bioavailability is approximately 64-90%. Time to peak concentration is about 6-12 hours.
Metabolism/Excretion: Amlodipine undergoes slow but extensive hepatic metabolism producing non-pharmacologically active metabolites. The elimination half-life is about 30-65 hours. Amlodipine is excreted by renal (about 59-62%) and biliary/fecal (about 20-25%).