Rentiapril (SA-446) is an angiotensin-converting-enzyme (ACE) inhibitor that has antihypertensive activity. This compound binds to ACE and blocks the conversion of angtiotensin I to angtiontensin II. Angiotensin II has vasoconstrictive activity, which rentiapril prevents, leading to vasodilation. Rentiapril has been shown to inhibit ADE activity more strongly and for longer periods than two other ACE inhibitors (captopril, and alacepril), and reduces blood pressure more quickly and for a longer time in patients with renovascular hypertension. Because rentiapril also decreases angiotensin II-induced aldosterone secretion by the adrenal cortex, it increases sodium excretion and (subsequently) water outflow.