[Hemodynamic effects of a new long-acting isosorbide dinitrate]

The following hemodynamic parameters were measured at rest and 1, 2, 4, 6, 8, 12 and 24 hours after 100 mg of ISDNSR p.o. in 10 patients with dilated cardiomyopathy (NYHA class III-IV): mean pulmonary artery, pulmonary capillary wedge (PCW) and arterial pressures (AP), and cardiac output (thermodilution). Plasma levels of ISDN were determined by capillary gas chromatography at the same intervals and correlated with the hemodynamic changes. PCW fell from 24 +/- 1.5 (SE) to 18 +/- 1.8 mm Hg after 1 hour (p less than 0.05) and after 2 hours to 16.9 +/- 1.6 mm Hg. This change was sustained for 8 hours. At 12 hours PCW had increased again to 21 +/- 1.5 mm Hg and at 24 hours to 22 mm Hg. AP dropped from 89 +/- 5 to 81 +/- 4 mm Hg at 1 hour (p less than 0.2) and remained 80-84 mm Hg for 8 hours. It returned to baseline levels at 12 hours. Heart rate, cardiac index, systemic vascular resistance, stroke index and left ventricular work index did not change significantly during the observation period. Plasma levels of ISDN remained between 3 and 12 ng/ml for 16 hours. Thus, ISDNSR is an effective long-acting nitrate preparation which reduces preload for 8-12 hours. After this interval, nitrate tolerance starts to develop.