- What is isosorbide mononitrate, and how does it work (mechanism of action)?
- What are the side effects of isosorbide mononitrate?
- What is the dosage for isosorbide mononitrate?
- Which drugs or supplements interact with isosorbide mononitrate?
- Is isosorbide mononitrate safe to take if I'm pregnant or breastfeeding?
- What else should I know about isosorbide mononitrate?
What is isosorbide mononitrate, and how does it work (mechanism of action)?
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
What are the side effects of isosorbide mononitrate?
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:
To reduce the risk of low blood pressure, patients should rise slowly from a sitting position.
What is the dosage for isosorbide mononitrate?
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.

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Heart Illustration Browse through our medical image collection to see illustrations of human anatomy and physiology See ImagesWhich drugs or supplements interact with isosorbide mononitrate?
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.
Is isosorbide mononitrate safe to take if I'm pregnant or breastfeeding?
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 else should I know about isosorbide mononitrate?
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.
Summary
Isosorbide mononitrate (Imdur, Ismo, Monoket) is in a class of drugs called nitrates. Isosorbide mononitrate (Imdur, Ismo, Monoket) is used to treat angina pectoris (heart pain, chest pain). Side effects, drug interactions, warnings and precautions, and safety during pregnancy should be reviewed prior to taking this medication.
Related Disease Conditions
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Congestive Heart Failure (CHF)
Congestive heart failure (CHF) refers to a condition in which the heart loses the ability to function properly. Heart disease, high blood pressure, diabetes, myocarditis, and cardiomyopathies are just a few potential causes of congestive heart failure. Signs and symptoms of congestive heart failure may include fatigue, breathlessness, palpitations, angina, and edema. Physical examination, patient history, blood tests, and imaging tests are used to diagnose congestive heart failure. Treatment of heart failure consists of lifestyle modification and taking medications to decrease fluid in the body and ease the strain on the heart. The prognosis of a patient with congestive heart failure depends on the stage of the heart failure and the overall condition of the individual.
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Chest Pain
Chest pain is a common complaint by a patient in the ER. Causes of chest pain include broken or bruised ribs, pleurisy, pneumothorax, shingles, pneumonia, pulmonary embolism, angina, heart attack, costochondritis, pericarditis, aorta or aortic dissection, and reflux esophagitis. Diagnosis and treatment of chest pain depends upon the cause and clinical presentation of the patient's chest pain.
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Dizziness
Dizziness is a symptom that often applies to a variety of sensations including lightheadedness and vertigo. Causes of dizziness include low blood pressure, heart problems, anemia, dehydration, and other medical conditions. Treatment of dizziness depends on the cause.
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Angina
Angina is chest pain due to inadequate blood supply to the heart. Angina symptoms may include chest tightness, burning, squeezing, and aching. Coronary artery disease is the main cause of angina but there are other causes. Angina is diagnosed by taking the patient's medical history and performing tests such as an electrocardiogram (EKG), blood test, stress test, echocardiogram, cardiac CT scan, and heart catheterization. Treatment of angina usually includes lifestyle modification, medication, and sometimes, surgery. The risk of angina can be reduced by following a heart healthy lifestyle.
Treatment & Diagnosis
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Report Problems to the Food and Drug Administration
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.
REFERENCE:
FDA Prescribing Information