ZANIPRESS

Lercanidipine is a calcium antagonist of the dihydropyridine group and inhibits the transmembrane influx of calcium into cardiac and smooth muscle. The mechanism of its antihypertensive action is due to a direct relaxant effect on vascular smooth muscle thus lowering total peripheral resistance.

Enalapril is hydrolysed via hepatic CES 1 to the active metabolite enalaprilat, which acts as an ACE inhibitor. ACE is a peptidyl dipeptidase which catalyses the conversion of angiotensin I to the vasoconstrictor substance angiotensin II and hence inhibition of ACE results in decreased plasma angiotensin II. This also leads to increased plasma renin activity and decreased aldosterone secretion. The mechanism of action of enalapril is therefore primarily via the suppression of the RAAS. However, ACE is identical to kininase II, and so enalapril may also exert its effects by blocking the degradation of bradykinin, a potent vasodepressor peptide.