isosorbide mononitrate, Imdur, Ismo, Monoket

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Pharmacy Author:

Omudhome Ogbru, PharmD

Omudhome Ogbru, PharmD

Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

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Medical and Pharmacy Editor:

Jay W. Marks, MD

Jay W. Marks, MD

Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

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GENERIC NAME: isosorbide mononitrate

BRAND NAMES: Imdur, Ismo, Monoket

DRUG CLASS AND MECHANISM: 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.

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.

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

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

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

PRESCRIBED FOR: Isosorbide mononitrate is used for the treatment and prevention of angina. It can be used to decrease the frequency and severity of anginal (chest pain) episodes and to reduce the need for sublingual (under the tongue) nitroglycerin.

DOSING: The recommended dose of isosorbide mononitrate is 20 mg of immediate release tablets 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.

DRUG INTERACTIONS: Sildenafil (Viagra), tadalafil (Cialis) 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 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.

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

NURSING MOTHERS: It is not known if isosorbide mononitrate is excreted in human breast-milk.

SIDE EFFECTS: 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.

Reference: FDA Prescribing Information

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