Antihypertensive efficacy of sustained-release verapamil.

The antihypertensive effects of immediate-release (IR) verapamil were compared with those of sustained-release (SR) verapamil in 58 patients. After an open-label (IR verapamil) study, patients were randomized into a double-blind study to continue receiving the same dose of IR verapamil three times daily or an equivalent dose of SR verapamil (240 to 480 mg) once daily. Blood pressure decreased from 149/98 to 139/90 mmHg (p less than 0.01) with IR verapamil and from 150/98 to 136/88 mmHg (p less than 0.01) with SR verapamil. Ambulatory blood pressure monitoring showed a similar response for the two formulations. Diastolic pressure was less than 90 mmHg in approximately 67% of the IR verapamil group and 61% of the SR verapamil group. Mean trough plasma concentrations of verapamil were 70 and 59 ng/ml at 2 and 4 weeks, respectively, after treatment with IR verapamil; the corresponding values were 70 and 94 ng/ml for the SR verapamil group. SR verapamil administered once daily is an effective antihypertensive medication in a selected group of patients and could afford better compliance.