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 to other times of the day.

METHODS

We studied the effects of a graded-release delivery system of diltiazem (diltiazem HCL extended release tablets) versus ramipril, both dosed at bedtime, on blood pressure (BP), heart rate, and the heart rate-systolic BP product during the first 4 hours after awakening in a double-blind, titration-to-effect trial. There were 261 men and women enrolled in the trial with an untreated sitting diastolic BP of 90 to 109 mm Hg and ambulatory daytime diastolic BP of 85 to 109 mm Hg. Patients were randomized to either diltiazem extended release (ER) tablets each evening (240 mg titrated to 360 mg and to 540 mg) or ramipril each evening (5 mg titrated to 10 mg and to 20 mg). Early morning assessments of BP, heart rate, and the heart rate-systolic BP product were performed using 24-hour ambulatory recordings after 10 weeks of therapy.

RESULTS

In each therapeutic group, 76% of patients were titrated to the highest possible dose. After 10 weeks of treatment, reductions in early morning BP by diltiazem ER tablets were significantly greater (-18/-15 mm Hg) than reductions by ramipril (-13/-8 mmHg, P <.005 for systolic BP and P <.001 for diastolic BP). Diltiazem ER tablets also led to greater reductions in morning heart rate and the heart rate-pressure product compared to ramipril. Reductions in mean 24-hour diastolic BP, heart rate, and the rate-pressure product were greater in patients treated with diltiazem ER tablets compared to ramipril, while reductions in 24-hour systolic BP were similar in each group. The observed adverse effects were not serious and incidences were similar for the 2 treatment groups.

CONCLUSIONS

These data demonstrate that bedtime administration of diltiazem ER, an agent designed to parallel the circadian rhythm of BP and heart rate, led to significantly greater early morning hemodynamic effects compared to the angiotensin-converting enzyme inhibitor ramipril, also dosed in the evening.