An open, long-term, multi-centre study of the anti-anginal efficacy and safety of isosorbide 5-mononitrate at low doses in patients with coronary heart disease.

A total of 250 patients with coronary heart disease diagnosed clinically, by ECG and in some cases by coronary angiography, was treated with isosorbide 5-mononitrate, 221 of the patients being treated for up to 6 months. In 181 patients previously treated with isosorbide dinitrate (ISDN)-retard, the mean daily dosage of nitrate was reduced from 77 mg (200 mg maximum) ISDN to 45 mg (120 mg maximum) isosorbide 5-mononitrate in long-term treatment. During previous treatment with ISDN-retard (with high doses in some cases: 80 to 200 mg daily in 48.6% of patients and 40 mg or less daily in only 33.1%), 4.5% of the patients were totally free of angina pectoris attacks. In the same patients, this proportion was 53.6% after administration of isosorbide 5-mononitrate for 6 months (dosage 40 mg daily or less in 67.4% of patients, 80 mg or more in 8.8% of patients). A substantial increase in subjective exercise tolerance and the reduction in incidence of angina pectoris was associated with a marked reduction in nitrate consumption for acute attacks. Isosorbide 5-mononitrate lowered slightly the blood pressure and heart rate. Treatment with isosorbide 5-mononitrate was withdrawn in 22 (8.8%) patients due to nitrate intolerance (headache in 7.6%) and in a further 7 (2.8%) patients for other reasons. Of patients completing 6-months' treatment, 9.9% reported one or more reversible undesirable reactions typical of nitrates at the start of the trial (compared with 6.8% in the pre-trial period). The incidence of such effects decreased to 1.4% after 6 months. The incidence of tolerable headache was 7.7% during the first week on isosorbide 5-mononitrate, decreasing to 0.9% after 24 weeks (5.9% in the pre-trial period). The laboratory parameters and subjective tolerability data confirmed the therapeutic safety of isosorbide 5-mononitrate.