ANTIHYPERTENSIVE EFFICACY AND ORTHOSTATIC TOLERANCE OF BUNAZOSIN VS NITRENDIPINE - A MULTICENTER DOUBLE-BLIND RANDOMIZED CONTROLLED-STUDY

A multicentre double-blind randomized controlled study was conducted i n 358 patients with mild to moderate essential hypertension. The goal was to compare the antihypertensive efficacy, tolerability, and in par ticular postural hypotension of the alpha(1)-adrenoreceptor blocker bu nazosin with the calcium channel blocker nitrendipine, Both treatment groups had comparable baseline blood pressure (BP) values, namely dias tolic BP (DBP) of 103.8 +/- 5.6 m mHg in the bunazosin group, and 103. 4 +/- 6.0 mm Hg in the nitrendipine group, respectively. Baseline syst olic BPs (SBP) were 149.7 +/- 14.4 mmHg (bunazosin) and 149.2 +/- 14.3 mm Hg (nitrendipine). After 12 weeks of therapy, reduction of DBP (-6 .1 +/- 11.7 mm Hg on bunazosin vs -6.9 +/- 9.9 mm Hg on nitrendipine; P = n.s.), and SEP (-4.4 +/- 14.3 mm Hg on bunazosin vs -7.0 +/- 14.4 mm Hg on nitrendipine; P = n.s.) was similar in both groups. During a provocative orthostatic tolerance test after the first dose, the incid ence of prae-collapses (ie termination of the test due to orthostatic complaints) was higher on bunazosin (17 vs 2; P < 0.05) but orthostati c dysregulation symptoms (symptom score 1.37 on bunazosin vs 0.95 on n itrendipine; n.s.) and collapses (four on bunazosin vs one on nitrendi pine; n.s.) occurred to a similar extent in both treatment groups. Thr ee and 9 weeks after treatment, no increased susceptibility to orthost atic stress compared to baseline could be found in either group. Under daily life conditions, the frequency of orthostatic dysregulation was identical in both groups (0.8%). Bunazosin, however, was far better t olerated with 43.8% of the patients complaining of adverse events as o pposed to 63.6% on nitrendipine (P < 0.001). The rate of early discont inuations due to adverse events was only 1.3% on bunazosin compared to 13.6% on nitrendipine (P < 0.001). In conclusion, bunazosin has a sim ilar antihypertensive efficacy as nitrendipine, Despite an initially h igher susceptibility to orthostatic stress under a provocative manoeuv er, bunazosin evoked the same low incidence of orthostatic dysregulati on symptoms as nitrendipine under daily life conditions, but was signi ficantly better tolerated than nitrendipine.