CONVERSION FROM IMMEDIATE-RELEASE TO EXTENDED-RELEASE DILITIAZEM IN ANGINA-PECTORIS

This multicenter, open-label, single crossover study examined 195 pati ents taking an immediate-release diltiazem tablet as chronic stable an gina therapy to determine if apparently logical methods of converting them to an extended-release, once-daily formulation were effective. Pa tients were converted from the immediate-release (Phase I) to an exten ded-release (Phase II) formulation of diltiazem on a mg-for-mg basis o r, when a similar dose was not available, to the next higher 120 mg do se. Weekly angina occurrences and nitroglycerin use, exercise testing at the end of each phase, and ambulatory electrocardiographic monitori ng (AEM) during the week prior to the exercise study were evaluated. T here was a statistically significant decrease in angina frequency and nitroglycerin consumption during Phase II. In the exercise studies, th ere was an insignificant increase in time to 1 mm ST-segment depressio n and total exercise time associated with a statistically significantl y lower end-exercise blood pressure and heart rate in Phase 11. In tho se patients who had ischemia during either phase on AEM, total ischemi c duration and ischemic episodes were insignificantly lower in Phase I I. All observations were similar in the subgroup of patients who were converted mg-for-mg. Adverse reactions were equal. Thus, in converting patients from an immediate- to an extended-release diltiazem formulat ion for the treatment of symptomatic coronary artery disease, it is re asonable to convert directly to the same or, if not available, the nex t higher available dose of the extended-release preparation.