Isosorbide dinitrate is in the class of drugs called nitrates, and it is used for treating and preventing angina or heart pain. Other nitrates include nitroglycerin (Nitrostat, Nitroquick, Nitrolingual, Nitro-Dur and others) and isosorbide mononitrate (Imdur, Ismo, Monoket). Isosorbide dinitrate is converted in the body to isosorbide mononitrate which is the active chemical.

Nitrates are vasodilators (dilators of blood vessels). Blood returning from the body in the veins must be pumped by the heart through the lungs and into the body's arteries against the high pressure in the arteries. In order to accomplish this work, the heart's muscle must produce and use energy ("fuel"), and this requires oxygen. Angina pectoris (angina) or "heart pain" is due to an inadequate flow of blood (and oxygen) to the muscle of the heart. Nitrates, including isosorbide dinitrate, improve the flow of blood and oxygen to the heart and reduce the work that the heart must do by dilating (expanding) the arteries and veins in the body. Dilation of the veins reduces the amount of blood that returns to the heart that must be pumped. Dilation of the arteries lowers the pressure in the arteries against which the heart must pump. As a consequence of both effects, the heart works less and requires less blood and oxygen. In addition, nitrates dilate the arteries that supply the heart with blood so that the heart receives more blood and oxygen. The FDA approved isosorbide dinitrate in January 1968.

Isordil, Isordil Titradose, Dilatrate-SR

GENERIC AVAILABLE: Yes

Yes

Headaches are the most common side effect of isosorbide dinitrate and usually are dose-related (increase with higher doses). Flushing may occur because isosorbide dinitrate dilates blood vessels. Isosorbide dinitrate may cause a drop in blood pressure when rising from a sitting position (orthostatic hypotension), causing dizziness, palpitations, and weakness. To reduce the risk of these side effects, patients should rise slowly from a sitting position.

Isosorbide dinitrate tablets can be taken with or without food. The sublingual tablets should be dissolved under the tongue and should not be crushed or chewed. Tolerance (reduced effect after several doses) may develop, so a drug free period of at least 14 hours is recommended. The recommended doses of isosorbide dinitrate are:

• Tablets: 5-40 mg 2 or 3 times daily
• Tablets: (sublingual): 2.5-5 mg 15 minutes before activities likely to cause chest pain. For treating chest pain, 2.5 to 5 mg is taken every 5 to 10 minutes.
• Tablets: (extended-release) and capsules (sustained-release): 40-80 mg once or twice daily.

Sildenafil (Viagra), tadalafil (Cialis) and vardenafil (Levitra) increase the blood pressure lowering effects of isosorbide dinitrate and may cause excessive blood pressure reduction. Patients taking isosorbide dinitrate should not take sildenafil (Viagra), tadalafil (Cialis), or vardenafil (Levitra). Severe blood pressure reduction, especially when changing posture, may occur when isosorbide dinitrate is combined with calcium channel blockers, for example, diltiazem (Cardizem, Tiazac, etc.) and verapamil (Calan, Verelan, etc.) which also reduce blood pressure.

There are no adequate studies of isosorbide dinitrate in pregnant women.

It is not known if isosorbide dinitrate is excreted in human breast-milk.

What preparations of isosorbide dinitrate are available?

Tablets (sublingual): 2.5 and 5 mg. Tablets (immediate release): 5, 10, 20, 30, and 40 mg. Tablets (extended release): 40 mg. Capsules (sustained release): 40 mg

How should I keep isosorbide dinitrate stored?

Isosorbide dinitrate should be stored at room temperature, 15 C - 30 C (59 F - 86 F).