isosorbide mononitrate (Imdur, Ismo, Monoket)

Isosorbide mononitrate is in the class of drugs called nitrates that are used for treating and preventing angina. Other nitrates include nitroglycerin (Nitrostat, NitroQuick, Nitrolingual, Nitro-Dur and others) and isosorbide dinitrate (Isordil Titradose, Dilatrate-SR, Isochron). 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") which requires oxygen brought to the heart by the blood. The FDA approved isosorbide mononitrate in December 1991.

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 mononitrate, correct the imbalance between the flow of blood and oxygen to the heart and the work that the heart must do by dilating 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.

What brand names are available for isosorbide mononitrate?

Imdur (discontinued brand), Ismo (discontinued brand), Monoket

Is isosorbide mononitrate available as a generic drug?

Yes

Do I need a prescription for isosorbide mononitrate?

Yes

Headaches are the most common side effect of isosorbide mononitrate and usually are dose related (increase with higher doses). Flushing may occur because isosorbide mononitrate dilates (enlarges) blood vessels. Isosorbide mononitrate may cause a severe drop in blood pressure when rising from a sitting position, causing: 

• dizziness,
• palpitations, and
• weakness.

To reduce the risk of low blood pressure, patients should rise slowly from a sitting position.

The recommended starting dose of isosorbide mononitrate is 5 to 10 mg of immediate release tablets twice daily. The dose can be increased to 10 mg twice daily after 2 to 3 days. The target does is 20 mg twice daily. The two doses should be administered 7 hours apart in order to avoid tolerance (decreased effect after several doses). The dose for extended release tablets is 30-240 mg once daily.

Sildenafil (Viagra), tadalafil (Cialis), avanafil (Stendra),and vardenafil (Levitra) increase the blood pressure lowering effects of isosorbide mononitrate and may cause excessive reductions in blood pressure. Therefore, patients taking isosorbide mononitrate should not receive sildenafil, tadalafil, avanafil or vardenafil.

Severe reductions in blood pressure, especially when changing posture (orthostatic hypotension), may occur when isosorbide mononitrate is combined with calcium channel blockers [for example, diltiazem (Cardizem, Dilacor, Tiazac and several others), verapamil (Calan, Verelan, Verelan PM, Isoptin, Isoptin SR, Covera-HS)], which also reduce blood pressure.

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

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

What preparations of isosorbide mononitrate are available?

Tablets (immediate release): 10, 20 mg. Tablets (extended release): 30, 60, 120 mg.

How should I keep isosorbide mononitrate stored?

Isosorbide mononitrate should be stored at room temperature, 15 C - 30 C (59 F - 86 F) in a tight, moisture- proof container.