[Non-invasive ambulatory blood pressure measurement over 24 hours: effects of labetalol on the rise of blood pressure in the early morning].

Three french specialist centers have included 19 hypertensive patients in an open cooperative study of the effect of labetalol (L = 200 to 400 mg b.i.d.) on the 24 hour blood pressure (24 h - B.P.) recording by a non invasive method (Spacelabs - Squibb Medical Systems), with a particular assessment of the early morning rise of BP. Each patient was subjected to 2 assessments at the end of a 14 days' placebo period and of a 28 days' treatment period. At the end of the study, the systolic (SBP) and diastolic (DBP). B.P. were significantly decreased at rest (p less than 0.001) and on the 24 hours recording (p less than 0.001). The reduction of B.P. was also significant on day period from 7 a.m. to 22 p.m. (p less than 0.001) and night period from 22 a.m. to 7 a.m. (p less than 0.05) as well as on the early morning period, 3 hours before and after waking (p less than 0.001). The heart rate was significantly reduced during the day (p less than 0.05) and was not on the night. The slope of the early morning rise of B.P. was marked after placebo and significantly decreased after labetalol with a reduction of 52% for SBP and 49% for DBP (p less than 0.001). These results show that labetalol has an antihypertensive effect over 24 hours with a marked effect on the early morning rise of B.P.