Effectiveness of antihypertensive medications in office and ambulatory settings: a placebo-controlled comparison of atenolol, metoprolol, chlorthalidone, verapamil, and an atenolol-chlorthalidone combination.

In a double-blind, crossover study, five white men with mild-to-moderate hypertension received placebo and fixed doses of atenolol, metoprolol, chlorthalidone, verapamil, and the combination of atenolol and chlorthalidone in a quasi-random order. Daily dosages were: atenolol, 100 mg; metoprolol, 200 mg; chlorthalidone, 50 mg; verapamil, 240 mg; and the same doses of atenolol and chlorthalidone in combination. Standard office and daytime ambulatory blood pressures were assessed at the end of each month-long trial. Atenolol, metoprolol, chlorthalidone, and verapamil controlled office blood pressure with similar reductions. Verapamil did not lower ambulatory blood pressure at this dose (which is lower than is now commonly used), but reductions in ambulatory blood pressure were similar for atenolol, metoprolol, and chlorthalidone. The combination of atenolol and chlorthalidone maintained blood pressure control more effectively than the single drug treatments in both office and ambulatory settings, and the combined hypotensive effects were additive. However, reductions in the office due to the combination appeared to overestimate hypotensive effectiveness in the ambulatory setting. This study suggests that the effectiveness of commonly prescribed antihypertensive regimens varies according to setting as well as drug, and that assessment of treatment effectiveness can be improved by automated ambulatory blood pressure monitoring.