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# Calcium Acetate
## Overview
Calcium acetate is an inorganic salt used to bind phosphate in the gastrointestinal tract, thereby reducing phosphate absorption. It also serves as a calcium supplement.
## Primary Indications
* **Hyperphosphatemia:** Primarily in patients with chronic kidney disease (CKD) on dialysis.
* **Calcium Supplementation:** To prevent or treat calcium deficiency.
## Adult Dosing
* **Hyperphosphatemia:**
* **Initial:** 500 mg to 1,000 mg (approximately 62.5 mg to 125 mg elemental calcium per dose) orally with meals.
* **Titration:** Doses should be individualized based on serum phosphate levels, aiming to keep serum phosphate < 5.5 mg/dL. Typical maintenance doses range from 1,000 mg to 2,000 mg per meal.
* **Maximum:** While not strictly defined, total daily elemental calcium intake should not exceed 4,000 mg from all sources (dietary and supplemental).
* **Calcium Supplementation:**
* Dosing varies widely based on individual need and dietary intake. Recommended daily allowances (RDAs) should be considered.
## Pediatric Dosing
* **Hyperphosphatemia:** Dosing is not well-established and should be individualized under specialist guidance. A common starting point may be 10-20 mg/kg/day of elemental calcium, divided with meals, titrating to phosphate levels. However, careful monitoring for hypercalcemia is crucial.
## Dose Adjustments
* **Renal Impairment:** Dose adjustment is inherent to the management of hyperphosphatemia in CKD. In patients with less severe renal impairment or those not on dialysis, caution and close monitoring of calcium and phosphate levels are necessary.
## Contraindications
* Hypercalcemia.
* Conditions causing hypercalcemia (e.g., certain malignancies, primary hyperparathyroidism).
* Ventricular fibrillation.
## Adverse Effects
* **Common:** Hypercalcemia, constipation, nausea, vomiting, abdominal pain.
* **Serious:** Hypercalcemia can lead to arrhythmias, hypophosphatemia, and potential vascular calcification.
## Key Drug Interactions
* **Tetracyclines and Quinolones:** Calcium acetate can chelate these antibiotics, reducing their absorption. Administer at least 2 hours before or 6 hours after these antibiotics.
* **Thyroid Hormones:** Calcium salts can decrease absorption of levothyroxine. Separate administration by at least 4 hours.
* **Biphosphonates:** May reduce absorption of bisphosphonates. Separate administration by at least 2 hours.
* **Digoxin:** Hypercalcemia can increase the risk of digoxin toxicity.
* **Thiazide Diuretics:** May increase serum calcium levels.
## Monitoring
* Serum calcium, phosphate, and alkaline phosphatase levels regularly, especially during initiation and dose titration.
* Monitor for signs and symptoms of hypercalcemia (e.g., polyuria, polydipsia, nausea, constipation, weakness, confusion).
* Periodic assessment of intact parathyroid hormone (iPTH) levels in patients with CKD.
## Clinical Pearls
* Administer calcium acetate with meals to maximize phosphate binding.
* Consider the total elemental calcium content from all sources when determining dosage.
* Patients on dialysis often require higher doses to control phosphate levels.
* Be vigilant for hypercalcemia, particularly in elderly patients or those with underlying cardiac conditions.
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant clinical guidelines before making any treatment decisions. Dosing and recommendations may vary based on individual patient factors and local protocols.*
