Pilot study of the effects of the angiotensin-converting enzyme inhibitor CI-906 on patients with essential hypertension.

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.