[Plasma levels of isosorbide dinitrate and its metabolites during intravenous infusion in surgical patients--effect of preoperative administration of isosorbide dinitrate].

Nineteen patients with ischemic heart disease were studied to determine plasma levels of isosorbide dinitrate (ISDN) and its metabolites, isosorbide-2-mononitrate (2-ISMN) and isosorbide-5-mononitrate (5-ISMN) for 6 hrs during intravenous administration of ISDN, using gas chromatography. Differences in plasma levels of these substances were also evaluated in patients with or without preanesthetic medication of ISDN. These patients ranging in ages from 42 to 80 years were administered ISDN intravenously at a rate of 1 micrograms.kg-1 x min-1 during anesthesia and surgery. Preanesthetic administration of ISDN consisted of transdermal application of 40 mg dose. Surgery included gastrectomy, pneumonectomy, extended cholecystectomy, radical mastectomy and so on under either enflurane anesthesia or neuroleptanesthesia. Plasma ISDN levels increased and reached a plateau 3 hrs after the start of intravenous infusion of ISDN in patients of both groups. Plasma 2-ISMN levels increased gradually and reached a plateau 5 hrs after the commencement of intravenous administration of ISDN in patients of both groups. Plasma 5-ISMN levels increased gradually reaching the peak 6 hrs after the start of intravenous infusion of ISDN in both groups. Plasma ISDN, 2-ISMN and 5-ISMN levels were slightly higher in patients who received preanesthetic ISDN than in those who did not receive preanesthetic ISDN. However, there were no statistical differences in plasma ISDN or 2-ISMN levels between the groups except prior to the infusion. On the contrary, plasma 5-ISMN levels were significantly higher in patients who received preanesthetic ISDN than in those who did not receive preanesthetic ISDN for 3 hrs after the start of the infusion.