Diltiazem is a calcium channel blocker used to treat angina pectoris, heart arrhythmias, and high blood pressure.
Summary of Interactions with Vitamins, Herbs, and Foods
In some cases, an 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.
 Avoid: Reduced drug absorption/bioavailability—Avoid these supplements when taking this medication since the supplement may decrease the absorption and/or activity of the medication in the body. | DHEA |
| Depletion or interference | None known |
| Side effect reduction/prevention | None known |
| Supportive interaction | 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
Dehydroepiandrosterone (DHEA)
Diltiazem has been shown to raise blood levels of DHEA and DHEA-sulfate in insulin-resistant, obese men with high blood pressure.1
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.2
Interactions with Foods and Other Compounds
Food
Diltiazem may be taken with or without food.3 Sustained-release diltiazem products should be swallowed whole, without opening, crushing, or chewing.4
In a study of healthy volunteers, ingestion of grapefruit juice at the same time as diltiazem resulted in higher blood levels of the drug than when it was taken with water.5 Studies with certain other medications suggest that grapefruit juice may affect drug availability, even if it is consumed at a different time of the day. Therefore, individuals taking diltiazem should probably avoid grapefruit and grapefruit juice.
References
1. Beer NA, Jakubowicz DJ, Beer RM, Nestler JE. Disparate effects of insulin reduction with diltiazem on serum dehydroepiandrosterone sulfate levels in obese hypertensive men and women. J Clin Endocrinol Metab 1994;79:1077–81.
2. Newall CA, Anderson LA, Phillipson JD. Herbal Medicines: A Guide for Health-Care Professionals. London: Pharmaceutical Press, 1996, 213–4.
3. Du Souich P, Lery N, Lery L, et al. Influence of food on the bioavailability of diltiazem and two of its metabolites following the administration of conventional tablets and slow-release capsules. Biopharm Drug Dispos 1990;11:137–47.
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, 149r–9t.
5. Christensen H, Asberg A, Holmboe AB, Berg KJ. Coadministration of grapefruit juice increases systemic exposure of diltiazem in healthy volunteers. Eur J Clin Pharmacol 2002;58:515–20.
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2006-09-07
