DRUG INTERACTIONS: Calcium can make it difficult for the body to absorb certain medications. Calcium products bind to quinolone (for example, ciprofloxacin) and tetracycline (for example, Sumycin) antibiotics in the intestine and can prevent their absorption into the body. To prevent this interaction, doses of quinolone and tetracycline antibiotics should be separated by three or more hours from doses of calcium.
Calcium carbonate-containing products reduce acidity in the stomach. The reduction of acid decreases the absorption of iron from the intestine. Therefore, doses of calcium and iron should be separated by a several hours.
Calcium products also bind to sodium polystyrene sulfonate (Kayexalate, a drug used to treat high levels of potassium) in the intestine and, therefore, may interfere with the action of Kayexalate. Doses of Kayexalate and calcium products should be separated by several hours.
Calcium products appear in breast milk but are considered safe during breastfeeding.
PREPARATIONS: Tablets Chewable: 500, 750, 1000, 1177 mg
STORAGE: Tablets should be stored at room temperature, 2 C and 25 C (36 F and 77 F).
How does calcium carbonate work?: Calcium is the fifth most abundant element in the body. Calcium is an important structural component of bone and teeth and also is necessary for the normal function of all muscles (skeletal, heart, and smooth muscles) and nerves as well as the normal clotting of blood. Prolonged, inadequate intake of calcium causes weak bones (osteoporosis). Products containing calcium carbonate are used to increase the intake of calcium in individuals whose diets are low in calcium. The National Institutes of Health recommend 1000 to 1500 mg of calcium per day as part of a regimen to prevent the loss of bone that is associated with aging. Calcium carbonate products contain 40% calcium (absorbable calcium). Therefore, a 1500 mg tablet of calcium carbonate provides 600 mg of calcium. Calcium carbonate is also used an antacid for treating stomach distress.
Medically reviewed by Eni Williams, PharmD, PhD
Reference: FDA Prescribing Information
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