Acute hypotensive effect of captopril in man modified by prostaglandin synthesis inhibition.

1 A study was carried out to investigate the possible contribution of prostaglandins in captopril-induced hypotension. 2 Healthy volunteers and patients with essential hypertension were given single oral doses of 25 mg and 50 mg captopril respectively before and after cyclo-oxygenase inhibition with indomethacin. 3 The acute hypotensive effect of captopril was not associated with changes in heart rate. As expected, captopril led to an increase in plasma renin activity, decrease in plasma angiotensin II, and decrease in plasma aldosterone concentration. 4 After acute indomethacin pretreatment the acute hypotensive effect of captopril was significantly blunted in volunteers and in the 14 hypertensive patients. Changes in plasma renin activity and angiotensin II were significantly lower from a lower baseline. 5 Prostaglandins may therefore be mediators of the initial captopril effect. The blunting effect of indomethacin should be taken into account under clinical conditions.