Isosorbide dinitrate,1,4:3,6-dianhydro-D-glucitol dinitrate (Isordil, Sorbitrate),occurs as a white, crystalline powder. Its watersolubility is about 1 mg/mL. Isosorbide dinitrate, as a sublingual or chewable tablet,is effective in the treatment or prophylaxis of acute anginalattacks. When it is given sublingually, the effect begins inabout 2 minutes, with a shorter duration of action thanwhen it is given orally. Oral tablets are not effective inacute anginal episodes; the onset of action ranges from 15to 30 minutes. The major route of metabolism involves denitrationto isosorbide 5-mononitrate. This metabolite has amuch longer half-life than the parent isosorbide dinitrate.As such, this particular metabolite is marketed in a tabletform that has excellent bioavailability with much less firstpassmetabolism than isosorbide dinitrate. Isosorbide ismarketed as a combination therapy with hydralazine underthe tradename BiDil specifically for African Americanswith CHF.
