Perindopril is a long acting angiotensin-converting enzyme inhibitor with a perhydroindole group and no sulphydryl radical. Perindopril is a pro-drug that is hydrolyzed to the active metabolite perindoprilat. Perindopril is rapidly absorbed, reaching peak plasma concentrations about 1 h after a single oral dose. Its bioavailability is greater than 70% and is not influenced by meals. Perindoprilat reaches peak plasma concentrations 3 to 4 h after administration. The blood pressure lowering effect of perindopril has been shown in animal models with spontaneous and renovascular hypertension. In hypertensive patients dose response studies have shown a significant and linear relationship between the dose and the activity of perindopril. The antihypertensive efficacy of 4 and 8 mg doses is significantly greater than that of 2 mg or of placebo. The maximal response is attained about 4 to 6 h after the first dose. As demonstrated by 24 h blood pressure recordings in ambulatory patients, the antihypertensive activity of perindopril was still significant 24 h after the last dose. Clinical trials have indicated that perindopril is at least as effective as usual therapeutic doses of captopril, atenolol or a combination of hydrochlorothiazide plus amiloride in mild to moderate essential hypertension. Oral administration of 4 to 8 mg od significantly reduced supine and standing systolic and diastolic blood pressure, and adequate diastolic blood pressure control was attained in about 60 to 70% of patients with monotherapy. In the majority of patients, hypertension was controlled with a daily dose of 4 mg.(ABSTRACT TRUNCATED AT 250 WORDS)