Nifedipine

Summary of Interactions with Vitamins, Herbs, and Foods
(for details about the summarized interactions, read the full article)

Avoid: Adverse interaction—Avoid these supplements when taking this medication because taking them together may cause undesirable or dangerous results.	Pleurisy root* Tobacco*
Check: Other—Before taking any of these supplements or eating any of these foods with your medication, read this article in full for details.	Grapefruit juice
Depletion or interference	None known
Side effect reduction/prevention	None known
Supportive interaction	None known
Reduced drug absorption/bioavailability	None known

Interactions with Herbs

Pleurisy root
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 calcium channel blockers.¹

Interactions with Foods and Other Compounds

Grapefruit juice
Ingestion of grapefruit juice has been shown to increase the absorption of felodipine (a drug similar in structure and action to that of nifedipine) and to increase the adverse effects of the medication in patients with hypertension. People taking nifedipine or similar drugs should not consume grapefruit juice or grapefruit, unless they have discussed it with their physician.²

Food
Nifedipine may be taken with or without food.³ Nifedipine products should be swallowed whole, without crushing or chewing.⁴

Tobacco
In a double-blind study of ten cigarette smokers with angina treated with nifedipine for one week, angina episodes were significantly reduced during the nonsmoking phase compared to the smoking phase.⁵ People with angina taking nifedipine should not smoke tobacco.

References

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

2. Bailey DG, Malcolm J, Arnold O, Spence JD. Grapefuit Juice-Drug Interactions. Br J Clin Pharmacol 1998;46:101–110.

3. Reitberg DP, Love SJ, Quercia GT, Zinny MA. Effect of food on nifedipine pharmacokinetics. Clin Pharmacol Ther 1987;42:72–5.

4. Threlkeld DS, ed. Diuretics and Cardiovasculars, Calcium Channel Blocking Agents. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Mar 1996, 149m–9n.

5. Deanfield J, Wright C, Krikler S, et al. Cigarette smoking and the treatment of angina with propranolol, atenolol, and nifedipine. N Engl J Med 1984;310:951–4.

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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 March 2005.