BACKGROUND

Therapeutic agents for the treatment of hypertension may differ in their efficacy during the early-morning period, a time when both morbid and mortal cardiovascular events are increased compared with other times of the day.

METHODS

We studied the effects of a chronotherapeutic delivery system of verapamil (controlled-onset extended release [COER]-24 system) dosed at bedtime versus conventional morning administration of both enalapril and losartan on the blood pressure (BP), heart rate, and the heart rate systolic BP product during the first 4 hours after awakening in a placebo-controlled, forced-titration trial. There were 357 men and women enrolled in the trial with an untreated sitting diastolic BP of 95 to 114 mm Hg and ambulatory daytime diastolic BP > or =85 mm Hg. Patients were randomized to either COER-verapamil hydrochloride each evening (240 mg titrated to 360 mg), enalapril each morning (10 mg titrated to 20 mg), losartan each morning (50 mg titrated to 100 mg), or placebo. Early morning assessments of BP, heart rate, and the heart rate systolic BP product were performed by use of 24-hour ambulatory recordings after 4 weeks (low dose) and 8 weeks (high dose) of therapy.

RESULTS

Results were similar at weeks 4 and 8 for all treatment groups except that the magnitude of change was greater at week 8. After 8 weeks of treatment, reductions in early morning BP by COER-verapamil were significantly greater (-15/-10 mm Hg) than enalapril (-9/-7 mm Hg, P <.01) and losartan (-8/-5 mm Hg, P <.001). COER-verapamil also led to greater reductions in morning heart rate, the rate-pressure product, and the rate-of-rise of BP compared with the other 2 active treatment groups. Reductions in mean 24-hour BP were greater in patients treated with COER-verapamil compared with placebo and losartan, and similar to reductions in patients treated with enalapril.

CONCLUSIONS

Bedtime administration of an agent designed to parallel the circadian rhythm of BP and heart rate led to significantly greater early morning hemodynamic effects compared with other conventional once-daily antihypertensive agents dosed in the morning.