Lisinopril is an antihypertensive agent useful in controlling high blood pressure by relaxing blood vessels. The drug works by inhibition of angiotensin-converting enzyme (ACE) in human subjects and animals. ACE is a peptidyl dipeptidase that catalyzes the conversion of angiotensin I to the vasoconstrictor, angiotensin II. Angiotensin II also stimulates aldosterone secretion by the adrenal cortex. The beneficial effects of lisinopril in hypertension and heart failure appear to result primarily from suppression of the renin-angiotensin-aldosterone system. Side effects include fever and chills, hoarseness, swelling, stomach pain, itching, and yellow eyes or skin.