Slow-release metoprolol in angina pectoris. A comparative study of a cardioselective beta-blocking drug, metoprolol, in ordinary and slow-release tablets (Durules) in the treatment of angina pectoris.

A double-blind cross-over study was undertaken to compare the effects of ordinary metoprolol tablets (tablets) 0.1 g b.i.d. and metoprolol slow-release tablets (Durules) 0.2 g once daily in 16 patients with angina pectoris. Initially, the patients were treated with placebo for 2 weeks, and then during the cross-over periods with either 1 tablet morning and evening or 1 Durules in the morning and 1 placebo in the evening. Standardized bicycle ergometer exercise tests with heart rate and blood pressure measurements were performed 2 hours after placebo, 2 hours after tablets and Durules, 12 hours after tablets and 24 hours after Durules. The patients kept diaries of their anginal attacks throughout the study. There were no statistically significant differences in total work between tablets and Durules when the values at 12 hours and 24 hours were compared. However, total work was significantly greater at 2 hours and at 12 hours after tablets and 24 hours after Durules than after placebo. Heart rate and systolic blood pressure during exercise were significantly decreased 24 hours after Durules compared to placebo. The heart rate was, however, lower 12 hours after tablets than 24 hours after Durules (p less than 0.05), although this slight difference in the degree of beta-blockade did not seem to be of clinical importance in these patients.