ANTIHYPERTENSIVE EFFICACY OF TWICE-DAILY CONTROLLED-RELEASE DILTIAZEM USING 24-HOUR INTRAARTERIAL BLOOD-PRESSURE MONITORING

The aim of the study was to examine the efficacy of a new controlled release formulation of diltiazem administered in a twice-daily dose in patients with essential hypertension using 24 hour intra-arterial ambulatory blood pressure monitoring. Sixteen patients (2 female) of mean age 53 years with mild to moderate essential hypertension, defined as a supine resting diastolic cuff blood pressure greater than or equal to 95 mmHg, were recruited to a sequential dose ranging study of controlled release (CR) diltiazem. After a six week run-in period without any anti-hypertensive medication, intraarterial blood pressure monitoring with 60 degrees tilt, isometric handgrip and bicycle exercise testing were performed. Patients were then treated for one week with CR diltiazem 120 mg b.i.d. If supine resting diastolic cuff blood pressure fell by < 10 mmHg compared to the last run-in value and remained > 90 mmHg, the dose was increased to 240 mg b.i.d. for a week, and if necessary to 360 mg b.i.d. for a week. Patients continued for further one month on the dose of CR diltiazem at which they achieved target blood pressure reduction. At the end of this maintenance treatment, 24 hour intra-arterial blood pressure monitoring was repeated. Twelve patients were satisfactorily controlled on 120mg b.i.d. CR diltiazem, three on 240 mg twice daily and one on 360 mg twice daily. During rest and exercise, blood pressure and heart rate were significantly lower after treatment with CR diltiazem than before treatment. The hypotensive effect of diltiazem was maintained throughout the 12 hour dosing interval and the early morning blood pressure response was blunted. No adverse effects or ECG abnormalities were reported. It was concluded that CR diltiazem 120 mg, administered twice daily to a total daily dose of between 240 mg and 720 mg, is effective and well tolerated in the treatment of mild to moderate essential hypertension.