A Study Design for Comparing the Effects of Missing Daily Doses of Antihypertensive Drugs

In this double-blind, 6-week study comparing once-daily oral betaxolol and atenolol, the study design allowed the effects of simulated drug noncompliance to be examined. Overall similar blood pressure and heart rate responses were seen in 114 patients with mild-to-moderate hypertension. Similarly, there was no statistically significant difference in percentage of patients achieving goal diastolic blood pressure reductions at the end of 6 weeks of active therapy (betaxolol, 87%, 46/53; atenolol, 82%, 44/54), and safety results overall were similar. However, when patients randomly received placebo for two consecutive treatment days in either the fifth or sixth week of the study to simulate the effect of missing doses, magnitude and duration of effect on systolic blood pressure (p = 0.006), diastolic blood pressure (p = 0.02) and heart rate (p = 0.001) were significantly greater for betaxolol than atenolol as calculated from 28-h ambulatory blood pressure monitoring data. Although betaxolol and atenolol monotherapy are equally effective in controlling blood pressure when taken consistently, the blood pressure and heart rate response with betaxolol is significantly superior for at least 24 h after missing a dose, an important consideration related to patient noncompliance. These results are compatible with the different elimination half-lives of each drug.