Plasma levels of isosorbide dinitrate and the isosorbide mononitrates after increasing doses of a retard preparation of isosorbide dinitrate.

Different doses of a retard preparation of isosorbide dinitrate (40, 80 and 120 mg) were given in a cross-over design with one week intervals to 6 patients with angina pectoris. Plasma concentrations of isosorbide dinitrate and of the isosorbide 2- and 5-mononitrates were measured by a gas-liquid chromatographic method. The concentrations of isosorbide dinitrate rose with the dose given, and with the highest dose, levels above 5 ng/ml were obtained for 12 hours. Concentrations of the mononitrates were much higher than those of the parent compound.