Isosorbide-5-mononitrate and isosorbide dinitrate retard in the treatment of coronary heart disease: a multi-centre study

A multi-centre study was carried out in 200 coronary patients to compare the efficacy and tolerance of isosorbide dinitrate retard (40 mg) and isosorbide-5-mononitrate (20 mg) with regard to the frequency of anginal attacks and consumption of sub-lingual (short acting) nitrates. After receiving treatment for 2 weeks with isosorbide dinitrate retard at a dosage of 2 or 3 tablets per day, only those patients continued the study who had a weekly average of 4 or more anginal attacks during this basal period. The selected patients were divided in 4 groups of 50 patients and received treatment for a further 4 weeks with either isosorbide dinitrate retard at a dosage of 2 tablets (Group D2) or 3 tablets (D3) per day or isosorbide-5-mononitrate at a dosage of 2 tablets (Group M2) or 3 tablets (Group M3) per day. A progressive improvement in symptoms was seen at the end of 2 and 4 weeks with both drugs. The greater therapeutic benefits were obtained in patients in Group M2; the greater difference was observed between Group M2 and D2 (p less than 0.01) and there were also significant differences (p less than 0.05) between Groups M2 and D3 and between Groups M3 and D3. Analysis of the results showed that the more frequently angina attacks had occurred during the basal period, the greater was therapeutic benefit obtained with isosorbide-5-mononitrate compared to isosorbide dinitrate retard at the end of the study. Heart rate at the end of the study showed a slight tendency to increase over initial levels in all groups. In contrast, systolic blood pressure decreased very significantly in all groups (p less than 0.001). Diastolic blood pressure also decreased in all groups but only to a highly significant degree in patients treated with isosorbide-5-mononitrate (p less than 0.001) and the two sub-groups M2 and M3 (p less than 0.005). In patients treated with isosorbide dinitrate retard, the reduction in diastolic pressure was only statistically significant when the 100 patients in the group were considered as a whole (p less than 0.05), while this was not the case for the two sub-groups D2 and D3. The most frequent side-effect was headache, which improved gradually. During treatment there was a progressive dissociation between reduction in the intensity and frequency of this adverse effect and the increasing anti-anginal action of the nitrates.