Clinical studies with captopril treatment of hypertensive patients

Haemodynamic and humoral effects of captopril were studied in patients with essential and renovascular hypertension. Captopril decreased significantly both systolic and diastolic blood pressure and moderately, it reduced also the heart rate. On the basis of the haemodynamic effects our patients could be divided into two groups: in patients where the total peripheral resistance (TPR) exceeded 2000 dyn x sec x cm-5 during rest, captopril exerted its hypotensive effect by decreasing TPR. In patients in whom TPR was lower, the hypotensive action could be attributed to the reduction of cardiac output (CO). Captopril increased plasma renin activity, and decreased the activity of angiotensin converting enzyme (ACE) in the plasma. In acute study captopril did not influence plasma noradrenaline level but increased it during long-term administration. It did not affect dopamine or adrenaline levels. Captopril had no effect on plasma beta-endorphin concentration, moreover, the opiate antagonist, naloxone, failed to antagonize its antihypertensive effect. Comparing the acute effects of Capoten (Squibb, USA) and Tensiomin (EGIS, HUNGARY) no significant differences were found.