抄録
Hemodynamic effects of short-term (6 weeks) oral urapidil 84.0±7.8mg/day, dilevalol 142±33 mg/day and acebutolol 444±26 mg/day were investigated in 48outpatients with essential hypertension (WHO stage I and II). Hemodynamic studieswere made in the supine position by radioisotope dilution technique using 131I humanserum albumin to measure total circulating blood volume (TCBV) and 99mTc in vivolabelled red cells to measure cardiac output and left ventiicular ejection fraction (LVEF).
These three drugs reduced blood pressure (P<0.005) with various changes in heartrate (urapidil, 73±3 to 71±2 bpm, ns; dilevalol, 63±2 to 59±1 bpm, P<0.025, acebutolol, 73±2 to 62±1 bpm, P<0.005). Cardiac index (CI) decreased slightly ithe acebutolol-and dilevalol-treated groups, though the change was not significant inthe latter. Urapidil did not induce a decrease in CI. LVEF tended to increase in thesethree groups, though the changes were not siginificant. Total peripheral resistanceindex (TPRI) tended to decrease in the dilevalol group (2, 885±118 to 2, 504±86dyne·sec·cm-5·m2, P<0.005) andand in the urapidil group (2, 749±193 to 2, 471±163dyne·sec·cm-5·m2, ns), but did not in the acebutolol.
Urapidil, dilevalol, and acebutolol were reported to have beta-blocking activity andintrinsic sympathomimetic activity (ISA) as common pharmacological properties.However, urapidil and dilevalol have alpha-blocking activity, acebutolol did not. Theresults in this study suggest that the less beta-blocking activity the drug has, the lesscardiosuppressive effects it induces, and the effects of cardiac blockade may beantagonized by ISA and afterload reduction for the heart.
Urapidil may induce a decrease in TPRI by vascular alpha-receptor blockingactivity, and its cardiac beta-blockade was not exhibited in this study, though thepossibility may exist that it supressed a reflex-induced tachycardia and increase incardiac pump function. ISA of dilevalol on the vasculature was reported to induceperipheral vasodilation in animal study, and this coincided with the results in this study, however, the decrease in TPRI may be partially influenced by vascular alpha-receptorblockade.
