Long term efficacy of a controlled-release formulation of isosorbide 5-mononitrate (Imdur) in angina patients receiving beta-blockers.

In a multicentre double-blind crossover study the clinical efficacy and tolerability of a controlled-release formulation, Durules, of isosorbide 5-mononitrate (Imdur) 60mg once daily was compared with placebo over 2 weeks in 70 patients with stable exercise-induced angina pectoris who were receiving concomitant long term beta-blockade. Isosorbide 5-mononitrate significantly improved exercise capacity and signs of myocardial ischaemia, while reducing the number of anginal attacks and consumption of short-acting glyceryl trinitrate tablets compared with beta-blocker therapy alone. During an open follow-up period of 1 year, there was no attenuation of the antianginal efficacy of isosorbide 5-mononitrate. The drug was well tolerated during both phases of the study, and the only significant adverse effect was headache, which rapidly disappeared during continued treatment.