Comparison of the time to onset of action on myocardial ischaemia following intravenous administration of isosorbide dinitrate and 5-isosorbide mononitrate in Chinese patients.

OBJECTIVE: The onset of action of intravenous isosorbide dinitrate (CAS 87-33-2, ISDN) and intravenous 5-isosorbide mononitrate (CAS 16051-77-7, 5-ISMN) were compared by measurement of the indicators of perfusion to ischaemic myocardium. METHODS: Twenty-five patients with coronary heart disease were randomly allocated to receive intravenous ISDN or 5-ISMN. The extent of myocardial ischaemia before infusion and at 3, 15 and 45 min after commencement of infusion was evaluated using 99mTc-MIBI myocardium tomography imaging and electrocardiograms. RESULTS: The perfusion defects were significantly reduced or resolved in 11 patients (84.1%) receiving ISDN and 2 patients (15.38%) receiving 5-ISMN at 3 min. At 15 min the improvement was significantly greater in the ISDN group than in the 5-ISMN group. The improvements of 99mTc-MIBI myocardial uptake ratio and electrocardiograms were statistically significant in the ISDN group at 3 min and 15 min compared to pre-infusion. Although a significant improvement appeared at 15 min in the 5-ISMN group, it was significantly less than that observed in the ISDN group (p < 0.05). After 45 min, there were improvements in ischaemia in both groups with the difference compared to pre-infusion being significant, and there was no statistically significant difference between the ISDN and 5-ISMN group. CONCLUSION: In patients with coronary heart disease with ischaemic episodes the onset of therapeutic activity was more rapid with intravenous ISDN compared to 5-ISMN. ISDN should be the preferred intravenous nitrate for acute ischaemic episodes where a rapid onset of therapeutic action is desired.