Risedronate is used to treat certain bone diseases. It is in a family of drugs known as bisphosphonates.
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.
 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. | Calcium* |
 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. | Antacids Calcium Food Iron Magnesium Zinc (absorption) Zinc (action) |
| 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
Calcium and Vitamin D
Short-term treatment with risedronate in people with hyperparathydoidism—a disorder characterized by high blood levels of calcium—resulted in lower calcium blood levels.1 Additional research is needed to determine whether people taking risedronate for Paget’s disease might develop low blood calcium levels. As a precaution, people with Paget’s disease should take supplemental calcium and vitamin D if dietary intake is inadequate. However, taking risedronate at the same time as calcium supplements reduces absorption of the drug.2 Therefore, people taking risedronate for Paget’s disease should take calcium supplements an hour before or two hours after taking the drug.
Minerals
Taking risedronate at the same time as iron, zinc, or magnesium may reduce the amount of drug absorbed.3 Therefore, people taking risedronate who wish to supplement with these minerals should take them an hour before or two hours after the drug.
Interactions with Foods and Other Compounds
Antacids
Taking risedronate at the same time as antacids containing calcium or magnesium may reduce absorption of the drug. Therefore, people taking risedronate should take calcium- or magnesium-containing antacids an hour before or two hours after the drug.
Food
One controlled study showed that taking risedronate either a half an hour before or two hours after a meal dramatically reduced absorption of the drug, compared with taking the drug one hour before or four hours after a meal.4 Consequently, people should take risedronate one hour before a meal or 4 hours after a meal, as long as the latter is at least one hour before the next meal.
References
1. Reasner CA, Stone MD, Hosking DJ, et al. Acute changes in calcium homeostasis during treatment of primary hyperparathyroidism with risedronate. J Clin Endocrinol Metab 1993;77:1067–71.
2. Sifton DW, ed. Physicians’ Desk Reference. Montvale, NJ: Medical Economics Company, Inc., 2000, 2504–6.
3. Sifton DW, ed. Physicians’ Desk Reference. Montvale, NJ: Medical Economics Company, Inc. 2000, 2504–6.
4. Mitchell DY, Heise MA, Pallone KA, et al. The effect of dosing regimen on the pharmacokinetics of risedronate. Br J Clin Pharmacol 1999;48:536–42.
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2006-09-07
