The bioavailability of ISDN varies widely, and it undergoes significant first-pass metabolism. The half-life of ISDN is about 1 hour.
Isosorbide mononitrate (ISMN) is the active metabolite of ISDN and is primarily used in the management of chronic stable angina. It is not FDA-approved for treating heart failure. It has high bioavailability and a longer half-life (4-6 hours) than ISDN.