The effect of isosorbide-5-mononitrate (5-ISMN) Durules on exercise tolerance in patients with exertional angina pectoris. A placebo controlled study.

Twenty-four patients with stable exercise-induced angina pectoris entered a double-blind cross-over study. Isosorbide-5-mononitrate (5-ISMN) 60 mg in a controlled release formulation (Durules) given once daily was compared with identical placebo. The exercise tolerance was determined by bicycle ergometry before and 3 h after a single dose of 5-ISMN and following one week's treatment with 5-ISMN and placebo. Nineteen patients completed the study. Exercise tolerance until the onset of chest pain and until 1 mm ST segment depression increased significantly 3 h after dose. The same increase was seen both after a single dose and the same dose under steady-state conditions. No increase was seen with placebo. The heart rate and systolic blood pressure reactions in the standing position were less pronounced 3 h after dose in steady-state than after a single dose of 5-ISMN. Headache was the only bothersome side-effect reported. The study demonstrates that 60 mg 5-ISMN in a Durules formulation given once daily has a significant anti-anginal effect and that tolerance does not develop.