Blood and tissue levels of [14C]isosorbide dinitrate after oral and intravenous administration to rat.

Rat blood and various tissues were analyzed for levels of isosorbide dinitrate (ISDN), an antianginal drug, after the administration of 14C-labeled compound. Unaltered [14C]ISDN was found in all tissues analyzed and in the circulating blood for up to 4 hours after p.o. or i.v. administration. These results clearly show that ISDN is not completely degraded in a single pass through the liver after either route of administration. ISDN concentration (nanograms of ISDN per gram wet weight of tissue) in vascular tissue were significantly greater than other tissues or the blood.