This drug is being marketed by both Merck and Zeneca. The Merck product is called Prinivil; Zeneca's product is called Zestril.

Prinivil is indicated for the treatment of hypertension, heart failure, and acute myocardial infarction. It may be used alone as initial therapy or concomitantly with other classes of antihypertensive agents. It is indicated as adjunctive therapy in the management of heart failure in subjects who are not responding adequately to diuretics and digitalis. It is also indicated for the treatment of hemodynamically stable subjects within 24 hours of acute myocardial infarction, to improve survival.

In most hypertensive subjects studied, onset of antihypertensive activity was seen at one hour after oral administration of an individual dose of Prinivil, with peak reduction of blood pressure achieved by six hours. Although an antihypertensive effect was observed 24 hours after dosing with recommended single daily doses, the effect was more consistent and the mean effect was considerably larger in doses of 20 mg or more than with lower doses. However, at all doses studied, the mean antihypertensive effect was substantially smaller 24 hours after dosing than it was six hours after dosing.

During baseline-controlled clinical trials in subjects receiving digitalis and diuretics, single doses of Prinivil resulted in decreases in pulmonary capillary wedge pressure, systemic vascular resistance, and blood pressure accompanied by an increase in cardiac output and no change in heart rate.

A multicenter, controlled, randomized, unblinded clinical trial was conducted in 19,394 subjects with acute myocardial infarction admitted to a coronary care unit. The trial was designed to examine the effects of short-term (6-week) treatment with Prinivil, nitrates, their combination, or no therapy. Subjects receiving Prinivil alone or with nitrates had an 11% lower risk of death compared to patients receiving no Prinivil at 6 weeks.

Prinivil was found to be generally well tolerated in controlled clinical trials. For the most part, the following adverse effects were mild and transient: fatigue, diarrhea, nausea, headache, and dizziness.

The effects of Prinivil in hypertension and heart failure appear to result primarily from suppression of the renin-angiotensin-aldosterone system. Inhibition of ACE results in decreased plasma angiotensin II, which leads to decreased vasopressor activity and to decreased aldosterone secretion.

When used in pregnancy during the second and third trimesters, ACE inhibitors can cause injury and even death to the developing fetus. When pregnancy is detected, Prinivil should be discontinued as soon as possible.