Pilot Study of the Effects of the Angiotensin‐Converting Enzyme Inhibitor CI‐906 on Patients with Essential Hypertension

Abstract: The effects of two single doses of the new oral nonsulfhydryl angiotensin‐converting enzyme (ACE) inhibitor CI‐906 on blood pressure and hormone levels are described in eight subjects with essential hypertension. Starting at 0.625 mg, doses were separated by a placebo day and doubled in consecutive patients until the full effect (obtained with 5 and 10 mg) was reached, at which point the remaining patients received the same dosage. All doses, including the smallest, caused ACE suppression to less than 1 per cent of baseline lasting for least 12 hours and remaining below 30 per cent at 48 hours, accompanied by a rise in plasma renin activity (by 10.9 ± 2.1 ng/ml/hr) and fall in aldosterone (by −12.6 ± 2.5 ng/100 ml). However, a clinically significant, though partial and short‐lived, effect on blood pressure was observed at 2.5 mg. The two highest doses produced similar effects in terms of magnitude of mean blood pressure lowering (by 26 ± 5 and 25 ± 2 mm Hg, respectively) and duration (varying from 12 to over 24 hours) regardless of pretreatment renin levels. There was no orthostatic hypotension, tachycardia, or other adverse reaction.