Casual versus ambulatory twenty-four-hour blood pressure measurement in a comparative study with bisoprolol or nitrendipine.

In a double-blind, placebo-controlled, randomly allocated study, the 24-h efficacy of a single morning dose of 10 mg of the beta-blocker bisoprolol (n = 17) versus 20 mg of the calcium channel antagonist nitrendipine (n = 19) was assessed using two different methods of blood pressure determination: (1) casual blood pressure determinations in the morning before the dose; and (2) ambulatory day-time (6 a.m. to 6 p.m.) and night-time (6 p.m. to 6 a.m.) blood pressure monitoring using a non-invasive automatic device (Spacelabs 90202). After 4 weeks both agents induced significant blood pressure reductions compared to the placebo period as assessed by both casual and ambulatory day-time readings, without significant differences in the blood pressure reductions induced by the two drugs (P less than 0.05). Ambulatory night-time values, however, showed a significant blood pressure reduction only for bisoprolol (from 138 +/- 16/84 +/- 12 to 129 +/- 15/77 +/- 11 mmHg); nitrendipine did not induce any significant systolic or diastolic blood pressure changes during this period (140 +/- 11/87 +/- 10 to 136 +/- 13/86 +/- 10 mmHg). Individual response rates were 47% for nitrendipine and 71% for bisoprolol. The incidence of side effects was comparable under both drugs. Our results indicate that bisoprolol was more effective over 24 h than nitrendipine. We also conclude that the value of casual blood pressure readings for the evaluation of therapeutic agents given once a day seems to be limited in comparison to 24-h ambulatory monitoring.