Bioavailability of isosorbide dinitrate from an oral therapeutic system and from tablet Sorbonit Prolongatum 20,0 in human volunteers.

The bioavailability of isosorbide dinitrate from an oral therapeutic system (OTS) and from tablet Sorbonit Prolongatum 20,0 mg in 6 volunteers employing a crossover method was studied. Concentrations of isosorbide dinitrate (1),2-mononitrate (2) and 5-mononitrate (3) are plotted as mean concentrations for all volunteers. As evident, the concentration-time curves are similar after administration of both OTS and tablet Sorbonit Prolongatum. Concentration of the nitrates in the serum is close to the maximum level starting 2 h after the drugs were administered. Such concentration is nearly constant for 7 h in the case of nonmetabolized 1 and for 9 h for its metabolites. 24 h after administration metabolites 2 and 3 were found in the serum of 5 subjects. Based on the experimental data, we calculated the areas under curves (AUC). The observed differences in AUC appeared statistically insignificant at the 95% confidence level for the two preparations studied in the case both 1 and its metabolites.