[Essential arterial hypertension. Effects of labetalol on blood pressure and renin-angiotensin system (author's transl)].

The effects of labetalol, an alpha- and beta-adrenoceptor blocking drug, on blood pressure, heart rate, plasma renin activity (PRA) and plasma aldosterone were studied in 17 adult patients with essential hypertension. Following a total dose of 1 g labetalol administered over a 48-hour period, there was a rapid and significant fall in systolic and diastolic BP averaging 16,5 +/- 7,9%/14,8 +/- 7,5% respectively supine, 18,7 +/- 8,3%/17,8 +/- 7,2% standing and 23,9 +/- 7,1%/16,8 +/- 10,3% after moderate exercise; 24 hours after labetalol was discontinued, the BP had gone up but was still below pretreatment values. Bradycardia remained slight throughout. During treatment a significant decrease in PRA (mean : 45%) was observed in all patients and found to correlate in standing position with changes in standing and post-exercise mean arterial pressure. There was no significant changes in plasma aldosterone. Side-effects were mild and limited to tingling of the scalp in 5 patients. No clinical symptoms of postural hypotension were recorded.