Isosorbide Dinitrate (ISDN) belongs to a class of medications called Nitrates. Nitrates are used to prevent and treat the symptoms of angina (chest pain). Angina is caused by lack of blood supply and oxygen to your heart. Nitrates work by relaxing blood vessels so that more blood and oxygen is supplied to the heart.
When you take this medication regularly on a long-term basis, it can help to treat angina by reducing the number of heart attacks that occur.
Nitrates can also be used with other medications for the treatment of heart failure, a condition where the heart is weak and is unable to pump enough blood to the rest of the body.