Isosorbide Mononitrate

Also indexed as: Imdur®, ISMO®, Isotrate®, Monoket®

Combination drugs: Imazin XL Forte®, Imazin XL®

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.

Safetychecker Summary for Isosorbide Mononitrate
(for details about the summarized interactions, read the full article)

Beneficial May be Beneficial: Supportive interaction—Taking these supplements may support or otherwise help your medication work better.

N-acetyl cysteine
Check Check: Other—Before taking any of these supplements or eating any of these foods with your medication, read this article in full for details.

Vitamin C
Depletion or interference

None known
Side effect reduction/prevention

None known
Reduced drug absorption/bioavailability

None known
Adverse interaction

None known

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 Dietary 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.

Interactions with Foods and Other Compounds

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:

1. 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.

2. 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.

3. Bassenge E, Fink N, Skatchkov M, Fink B. Dietary supplement with vitamin C prevents nitrate tolerance. J Clin Invest 1998;102:67–71.

4. Threlkeld DS, ed. Diuretics and Cardiovasculars, Antianginal Agents, Nitrates. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Apr 1992, 143e.

5. 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.

6. Threlkeld DS, ed. Diuretics and Cardiovasculars, Antianginal Agents, Nitrates. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Apr 1992, 143e.

7. Threlkeld DS, ed. Diuretics and Cardiovasculars, Antianginal Agents, Nitrates. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Apr 1992, 143e.