Evaluation of effectiveness and tolerability of isosorbide mononitrate during a three-year period in patients with angina pectoris.

The antianginal effect and tolerability of isosorbide mononitrate (ISMN), 20 mg 2-3 times daily, orally were investigated in an open study in 28 patients, suffering from coronary heart disease and stable angina pectoris. Ergometric exercise tests were carried out before treatment and 2 h after drug intake, every 3 months during the first year and at 6-month intervals during the following 2 years. At the conclusion of the 3-year study the reduction of ST-segment depression, which had amounted to 58% after 1 year, could be improved to 78% (p less than 0.01). The frequency of angina was markedly reduced during the treatment with ISMN. While 14 of the patients had more than 3 episodes per day prior to the study, 16 patients were symptom-free at the end of the three years' therapy, and none of the patients had more than 1 or 2 attacks per day. The consumption of sublingual nitroglycerin diminished by 94% after one year and by 98% after 3 years of therapy (p less than 0.01). Headache was the only adverse effect observed in some of the patients (at the initiation of the treatment only). In conclusion this study demonstrated (1) the good tolerability of ISMN, at the doses used, and (2) the fact that the antianginal efficacy may be enhanced during the course of the therapy.