It's an ACE inhibitor for hypertension. Inhibition of ACE results in a decrease in plasma angiotensin II, leading to decreased vasoconstriction and a small decrease in aldosterone secretion and plasma aldosterone concentrations. Although the decrease in aldosterone is small, it can result in small increases in serum potassium. Slight increases in serum potassium have been observed in some hypertensive patients treated with benazepril alone. Essentially no change in mean serum potassium was seen in patients treated with benazepril and a thiazide diuretic .