Metoprolol

Also indexed as: Apo-Metoprolol®, Arbralene®, Betaloc-SA®, Betaloc®, Lopresor SR®, Lopressor®, Mepranix®, Novo-Metoprol®, Nu-Metop®, PMS-Metoprolol®, Toprol® XL

Combination drugs: Co-Betaloc SA®, Co-Betaloc®, Lopressor® HCT

Metoprolol is a beta-blocker drug used to reduce the symptoms of angina pectoris (chest pain), lower blood pressure in people with hypertension, and treat people after heart attacks. Metoprolol is available alone and in a combination product used to lower blood pressure.

Summary of Interactions with Vitamins, Herbs, and Foods
In some cases, a herb or supplement may appear in more than one category, which may seem contradictory. For clarification, read the full article for details about the summarized interactions.

May be Beneficial: Depletion or interference—The medication may deplete or interfere with the absorption or function of the nutrient. Taking these nutrients may help replenish them.	High-potassium foods* Pleurisy root* Potassium supplements*
Avoid: Adverse interaction—Avoid these supplements when taking this medication because taking them together may cause undesirable or dangerous results.	Alcohol High-potassium foods* Pleurisy root* Potassium supplements*
Side effect reduction/prevention	None known
Supportive interaction	None known
Reduced drug absorption/bioavailability	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

Potassium
Some beta-adrenergic blockers (called “nonselective” beta blockers) decrease the uptake of potassium from the blood into the cells,¹ leading to excess potassium in the blood, a potentially dangerous condition known as hyperkalemia.² People taking beta-blockers should therefore avoid taking potassium supplements, or eating large quantities of fruit (e.g., bananas), unless directed to do so by their doctor.

Interactions with Herbs

Pleurisy root(Asclepius tuberosa)
As pleurisy root and other plants in the Aesclepius genus contain cardiac glycosides, it is best to avoid use of pleurisy root with heart medications such as beta-blockers.³

Interactions with Foods and Other Compounds

Food
Food increases the absorption of metoprolol.⁴ Metoprolol should be taken at the same time every day⁵ always with or always without food.

Alcohol
Metoprolol may cause drowsiness, dizziness, lightheadedness, or blurred vision.⁶ Alcohol may intensify these effects and increase the risk of accidental injury. To prevent problems, people taking metoprolol should avoid alcohol.

References
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1. Rosa RM, Silva P, Young JB, et al. Adrenergic modulation of extrarenal potassium disposal. N Engl J Med 1980;302:431–4.

2. Lundborg P. The effect of adrenergic blockade on potassium concentrations in different conditions. Acta Med Scand Suppl 1983;672:121–6 [review].

3. Newall CA, Anderson LA, Phillipson JD. Herbal Medicines: A Guide for Health-Care Professionals. London: Pharmaceutical Press, 1996, 213–4.

4. Melander A, Danielson K, Schersten B, Wahlin E. Enhancement of the bioavailability of propranolol and metoprolol by food. Clin Pharmacol Ther 1977;22:108–12.

5. Threlkeld DS, ed. Diuretics and Cardiovasculars, Beta-Adrenergic Blocking Agents. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Oct 1992, 158p–8q.

6. Threlkeld DS, ed. Diuretics and Cardiovasculars, Beta-Adrenergic Blocking Agents. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Feb 1993, 158p–8q.

Please read the disclaimer about the limitations of the information provided here. Do NOT rely solely on the information in this article.

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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 chemist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires March 2007.

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