Amlodipine is a dihydropyridine calcium antagonist which inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle. It has greater effect on vascular smooth muscle cells than on cardiac muscle cells; Amlodipine is a peripheral arterial vasodilator that causes reduction in peripheral vascular resistance and reduction in blood pressure. Serum calcium concentration is not affected by Amlodipine.
Benazepril inhibits angiotensin-converting enzyme (ACE). ACE is a peptidyl dipeptidase that catalyzes the conversion of angiotensin I to the vasoconstrictor substance angiotensin II. Angiotensin II also stimulates aldosterone secretion by the adrenal cortex. Inhibition of ACE results in decreased plasma angiotensin II, which leads to decreased vasopressor activity and aldosterone secretion. Mechanism through which Benazepril lowers blood pressure is believed to be primarily suppression of the renin-angiotensin-aldosterone system, Benazepril has an antihypertensive effect even in patients with low-renin hypertension.