DOSE-RANGING STUDY OF A NEW, ONCE-DAILY DILTIAZEM FORMULATION FOR PATIENTS WITH STABLE ANGINA

A double-blind safety and efficacy dose-ranging study was conducted wi th a new, once-daily, extended-release (XR) diltiazem hydrochloride fo rmulation (Dilacor XR(R), Rhone-Poulenc Rorer, Collegeville, PA) in 18 9 patients with chronic stable angina pectoris. After a a-week placebo lead-in phase, the patients were randomly assigned to 1 of 4 once-dai ly, fixed-dose treatment groups: placebo, XR diltiazem 120 mg, 240 mg, or 480 mg. Extended-release diltiazem, at 240-mg and 480-mg once-dail y doses, significantly improved (P < .05) total exercise time during t readmill exercise tolerance testing after 2 weeks of treatment when as sessed 24 hours after the previous dose. These increasing doses of XR diltiazem were associated with incremental improvements in exercise to lerance. Outpatient Junction, as assessed by frequency of anginal atta cks, nitroglycerin use, and ambulatory electrocardiogram (Holter, Scol e Engineering Culver City, CA) monitoring of ischemic events, was also improved by XR diltiazem. This extended-release diltiazem formulation can be clinically titrated within the 120- to 480-mg dosing range, pe rmitting effective once-daily administration for treating chronic stab le angina.