SYSTEMIC, REGIONAL AND CEREBRAL HEMODYNAMIC-EFFECTS OF A NEW ANGIOTENSIN-CONVERTING ENZYME-INHIBITOR, IMIDAPRIL, IN HEALTHY-VOLUNTEERS

The effects of two single oral doses (5 mg and 20 mg) of a new angiote nsin I-converting enzyme inhibitor, imidapril, on a) systemic hemodyna mics (arterial pressure, heart rate, cardiac output), b) brachial and common carotid arteries' hemodynamics (diameter and blood flow, pulsed Doppler technique), c) cerebral hemodynamics (middle cerebral artery mean blood flow velocity, transcranial Doppler technique), and d) biol ogical parameters (plasma converting enzyme activity, active plasma re nin, plasma aldosterone, catecholamines, and atrial natriuretic factor ) were investigated and compared with those of a placebo during the 24 h period following administration in a randomized, double-blind, cros s-over study performed in six healthy volunteers. Imidapril induced a strong, dose dependent and sustained inhibition of plasma converting e nzyme activity and at the 20 mg dose an increase in active plasma reni n. Other investigated biological parameters were not drug-affected. Im idapril, whatever the dose, did not significantly affect systemic hemo dynamic parameters. Imidapril, 20 mg, significantly increased common c arotid artery blood flow and diameter and brachial artery diameter. Br achial blood flow also tended to increase but this was not significant . The middle cerebral artery mean blood flow velocity investigated in only five volunteers, underwent spontaneous variations after placebo, and these variations were not affected by imidapril, suggesting that i midapril, whatever the dose, does not influence cerebral blood flow. T hus, imidapril's vasodilating properties apparently affect only the mu scular (brachial artery) and cutaneous (external carotid artery) terri tories, but do not influence the cerebral vascular bed.