Bedtime administration of graded-release diltiazem in patients with inadequate BP control: a tolerability and efficacy study.

Background: Achievement of target BP is a challenge in patients attending family practice. The long duration between administration of the last bedtime dose of antihypertensive medication and the physiologic early morning surge in BP makes it difficult to achieve satisfactory BP control.

Objective: To determine whether a new graded-release preparation of diltiazem (diltiazem XC), taken once daily at bedtime, will show an acceptable adverse-effect profile as well as improved BP control.

Study Design/setting: This is an open label, observational study in an ambulatory care setting.

Patients: 954 patients with mild to moderate hypertension and BP not at target levels were attended by 85 physicians. Group 1 patients were receiving a diltiazem preparation and group 2 patients were not receiving any diltiazem preparation at baseline.

Intervention: Group 1 patients were given diltiazem XC at the same dose as the prestudy diltiazem. Treatment with diltiazem XC 180 mg was initiated in group 2 patients. Diltiazem XC was taken once daily at bedtime in both groups.

Main Outcome Measure: The predetermined main outcome measure was the development of adverse events with diltiazem XC when changing or adding the study medication. The secondary outcome measure was the proportion of patients who achieved target BP levels.

Results: Moderate or severe adverse events occurred in 8.7% of patients. Although 21.8% of patients reported either new or worsening adverse events after starting diltiazem XC, the large majority of adverse events were mild in severity. The most frequent moderate or severe adverse events were headache (2.0%) and constipation (1.7%). More patients in group 2 reported adverse events compared with patients in group 1. Target BP levels were achieved in 47.8% (95% CI 44.3, 51.3) of patients completing the 8- to 12-week treatment. No difference was found in the proportion of patients at target BP levels in groups 1 and 2.

Conclusion: Diltiazem XC, when used in an ambulatory care setting for patients who have not achieved BP targets, shows an acceptable adverse-effect profile and results in an important improvement of BP control.