Also indexed as: Calan®, Covera-HS®, Isoptin®,
Verelan®
Summary of
Interactions with Vitamins, Herbs, and Foods
(for details about the summarized interactions, read the full article)
 May be Beneficial: Side effect
reduction/prevention—Taking these supplements may help reduce the likelihood and/or
severity of a potential side effect caused by the medication. |
Calcium (for people with high blood pressure)
Fiber
Fluid
|
 Avoid: Adverse interaction—Avoid these supplements
when taking this medication because taking them together may cause undesirable or dangerous
results. |
Calcium (for people with high blood pressure)
Pleurisy root*
Vitamin D*
|
 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
|
| 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
Calcium
Calcium supplementation has been reported to reverse the blood pressure-lowering actions of
this drug when used to treat arrhythmias.1 2 It remains unclear whether
people taking verapamil for the purpose of lowering blood pressure should avoid calcium
supplementation. These people should discuss the matter with the prescribing doctor.
On the other hand, people who take verapamil to treat other conditions, such as angina or
heart arrhythmias, should discuss with their physicians the possibility of using low-level (as
little as 27 mg per day) calcium supplementation, to reduce excessive blood pressure-lowering
actions caused by verapamil in those who do not have high blood pressure.3
Vitamin D
Vitamin D may interfere with the effectiveness of verapamil.4 People taking
verapamil should ask their doctor before using vitamin D-containing supplements.
Fluid and Fiber
Constipation is a common side effect of verapamil
treatment.5 Increasing fluid and
fiber intake can ease constipation.
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.6
Interactions with Foods and Other Compounds
Grapefruit juice
Grapefruit juice may increase verapamil blood levels.7 The importance of this
interaction regarding verapamil effectiveness and side effects is unknown. Until more is
known, it makes sense for people taking this drug to either avoid drinking grapefruit juice
entirely or drink grapefruit juice only under the careful monitoring and supervision of the
prescribing doctor. In theory, this last possibility might allow for a decrease in drug dose,
but it could be dangerous in the absence of diligent monitoring. The same effects might be
seen from eating grapefruit as from drinking its juice.
References
1. Haft JI, Habbab MA. Treatment of atrial arrhythmias. Effectiveness of
verapamil when preceded by calcium infusion. Arch Intern Med
1986;146:1085–9.
2. Weiss AT, Lewis BS, Halon DA, et al. The use of calcium with verapamil
in the management of supraventricular tachyarrhythmias. Int J Cardiol
1983;4:275–80.
3. Kuhn M, Schriger DL. Low-dose calcium pretreatment to prevent
verapamil-induced hypotension. Am Heart J 1992;124:231–2.
4. Threlkeld DS, ed. Diuretics and Cardiovasculars, Calcium Channel
Blocking Agents. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and
Comparisons, Nov 1992, 150–b.
5. Threlkeld DS, ed. Diuretics and Cardiovasculars, Calcium Channel
Blocking Agents. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and
Comparisons, Nov 1992, 150–b.
6. Newall CA, Anderson LA, Phillipson JD. Herbal Medicines: A Guide
for Health-Care Professionals. London: Pharmaceutical Press, 1996, 213–4.
7. Holt GA. Food & Drug Interactions. Chicago: Precept
Press, 1998, 274–5.
Copyright © 2003 Healthnotes, Inc. All rights reserved.
www.healthnotes.com
Please read the disclaimer
about the limitations of the information provided here. Do NOT rely solely on the information
in this article.
Learn more about Healthnotes, the company.
Learn more about the authors of Using
Medicines with Vitamins and Herbs
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 July 2004.