Ramipril

Ramipril is oral angiotensin-converting enzyme (ACE) inhibitor used in the treatment of hypertension, heart failure. Ramipril is actually an inactive prodrug that is converted in the liver to itat, the active moiety, whose antihypertensive activity is sufficiently long to allow for once-daily administration. The pharmacodynamic characteristics of it most closely resemble those of benazepril, fosinopril, and quinapril, all of which are prodrugs. The active metabolite, itat, competes with angiotensin-converting enzyme for the substrate angiotensin I, blocking its conversion to angiotensin II, which is a potent vasoconstrictor and negative-feedback mediator for renin activity. Lower levels of angiotensin II produce a drop in blood pressure and a rise in plasma renin. It also inhibits Kininase II (identical to ACE), an enzyme that degrades bradykinin, a potent vasodilator, to inactive peptides, resulting in increased bradykinin levels. Bradykinin-induced vasodilation is thought to be of secondary importance in the blood-pressure lowering effect. A bradykinin mechanism may, however, contribute to ACE-inhibitor-induced angioneurotic edema.