Casual versus 24-hour ambulatory blood pressure recording in the evaluation of chronic administration of sustained-release verapamil.

Although ambulatory blood pressure monitoring has been used widely for the evaluation of antihypertensive treatment, little information is available regarding the comparison between this method and casual BP measurement during drug trials. In our study, we tested the efficacy of a new formulation of verapamil, 240 mg sustained-release tablets, and compared the degree of BP reduction as detected by casual (standard mercury manometer) and by 24-hour ambulatory recording (Spacelab ICR 5300). A statistically significant fall in casual BP was observed after verapamil with respect to placebo. Moreover, 24-hour, waking and sleeping ambulatory BPs were significantly reduced by verapamil. The mean BP reduction was similar for office (20.1/16.1 +/- 4.3/3.1 mmHg) and for day-time ambulatory monitoring (13.4/10.7 +/- 4.2/1.9 1.9 mmHg), but no correlation was found between BP fall recorded by the two techniques for individual subjects. This study suggests that sustained-release verapamil is an effective antihypertensive drug. Individual mean BP reduction outside the clinic may not be predicted from office readings and therefore ambulatory BP recording seems to provide a better basis for testing the efficacy of drugs.