各種β遮断薬の血圧日内変動プロフィールに及ぼす影響

Abstract

The purpose of this study was to investigate the effects of various beta-blockers on blood pressure (BP) and pulse rate (PR) profiles of 77 patients with essential hypertension (49 men and 28 women aged 56±16 years) and 86 normotensive individuals (controls).The drugs tested were atenolol (50 mg), nipradilol (6 mg), metoprolol (80 mg), and pindolol (10 mg). Each drug was randomly administered to a subgroup of essential hypertensives twice a day. BP and PR were noninvasively measured at 30-min intervals for 24 hours using an ABPM-630 (Nippon Colin Ltd.) before and 4 weeks after the start of treatment. The effects of each drug on the level (MESOR) and the pattern (amplitude and acrophase) of diurnal variations in the periodic regression curve, which fitted data to a periodicity of 24 and 12 hours, were investigated using periodic analysis of covariance.There was no significant difference in BP or PR levels between all groups before treatment. The mean 24-hour systolic blood pressure (SBP), diastolic blood pressure (DBP), and PR were significantly (p<0.01) reduced after treatment in each group; there was no significant difference in the degree of SBP reduction between the hypertensive groups. DBP reduction was significantly (p<0.01) greater in the nipradilol group (-13 mmHg) than in the pindolol group (-5 mmHg), but no significant difference was found between the atenolol or metoprolol groups and the other 3 groups. There was a significant (p<0.01) change in PR levels after treatment between the atenolol group (-8 bpm) and the metoprolol (-3bpm) or pindolol groups (-4 bpm).The diurnal BP or PR patterns of all groups before treatment were basically the same as those of the normal controls. The diurnal post-treatment pattern of the atenolol and nipradilol groups remained the same as that of the normal controls, but that of the meto-prolol and pindolol groups was significantly (p<0.05) different compared with the controls. The reason for this was that atenolol and nipradilol caused proportional daytime and nighttime reductions, while metoprolol had little effect on the morning BP and pindolol had a lesser effect during sleep.Metoprolol is relatively short acting and pindolol has intrinsic sympathetic activity.Thus, different beta-blockers have specific hypotensive or depressive effects on the BP and PR profiles; these characteristics seem important to consider in the treatment protocol of individual hypertensive patients.