Isosorbide Mononitrate

Alternative Medicine
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Also indexed as:

Imdur, ISMO, Isotrate, Monoket

Isosorbide mononitrate (ISMN) is a member of the nitrate family of drugs used to prevent angina (chest pain). It is available in immediate-release and extended-release products.

Herbs

Summary of Interactions for Isosorbide Mononitrate

Depletion or interference	None known
Adverse interaction	None known
Side effect reduction/prevention	None known
Supportive interaction	N-acetyl cysteine
Reduced drug absorption/bioavailability	None known
Other (see text)	Vitamin C

An asterisk (*) next to an item in the summary indicates that the interaction is supported only by weak, fragmentary, and/or contradictory scientific evidence.

Interactions with Supplements

N-acetyl cysteine (NAC)

In a double-blind trial, sustained-release ISMN plus oral NAC (2,400 mg twice per day) for two days led to significantly longer exercise time than ISMN plus placebo.¹ This outcome suggests that NAC may have increased the efficacy of ISMN. There were no differences in side effects between the two groups.

Vitamin C

Some persons taking nitroglycerin or isosorbide mononitrate may find that it loses efficacy over time. This is because the body adapts to the drug, a process known as developing tolerance. One study found that taking 2 grams three times daily of vitamin C can decrease this effect when nitroglycerin patches are simultaneously used.² Similar benefits have been confirmed in another study.³ However, it should be noted that it is also possible to avoid tolerance to these drugs by simply changing the dosing schedule. People taking ISMN or nitroglycerin should talk with their pharmacists about avoiding drug tolerance.

Other Interactions

Food

Isosorbide mononitrate should be taken on an empty stomach with a glass of water.⁴ Imdur® may be taken with or without food⁵ and should be swallowed whole, without chewing or crushing.⁶

Alcohol

Isosorbide mononitrate causes low blood pressure. Alcohol may increase this effect, leading to dangerously low blood pressure and other side effects.⁷ To prevent problems, people taking isosorbide mononitrate should avoid alcohol.

References

Svendsen JH, Klarlund K, Aldershvile J, Waldorff S. N-acetylcysteine modifies the acute effects of isosorbide-5-mononitrate in angina pectoris patients evaluated by exercise testing. J Cardiovasc Pharmacol 1989;13:320-3.
Watanabe H, Kakihana M, Ohtsuka S, Sugishita Y. Randomized, double-blind, placebo-controlled study of the preventive effect of supplemental oral vitamin C on attenuation of development of nitrate tolerance. J Am Coll Cardiol 1998;31:1323-9.
Bassenge E, Fink N, Skatchkov M, Fink B. Dietary supplement with vitamin C prevents nitrate tolerance. J Clin Invest 1998;102:67-71.
Threlkeld DS, ed. Diuretics and Cardiovasculars, Antianginal Agents, Nitrates. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Apr 1992, 143e.
Kosoglou T, Kazierad DJ, Schentag JJ, et al. Effect of food on the oral bioavailability of isosorbide-5-mononitrate administered as an extended-release tablet. J Clin Pharmacol 1995;35:151-8.
Threlkeld DS, ed. Diuretics and Cardiovasculars, Antianginal Agents, Nitrates. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Apr 1992, 143e.
Threlkeld DS, ed. Diuretics and Cardiovasculars, Antianginal Agents, Nitrates. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Apr 1992, 143e.

Last Review: 09-01-2007

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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires September 2008.

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