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# Calcium Acetate
## Overview
Calcium acetate is a phosphate binder used primarily in patients with end-stage renal disease (ESRD). It is highly effective at binding dietary phosphorus in the GI tract to form insoluble calcium phosphate, which is then excreted in feces. It contains approximately 25% elemental calcium by weight.
## Primary Indications
* Reduction of serum phosphorus in patients with hyperphosphatemia associated with chronic kidney disease (CKD).
## Adult Dosing
* **Initial Dose:** 667 mg to 1,334 mg (1 to 2 capsules/tablets) administered orally with each meal.
* **Titration:** Adjust based on serum phosphate levels.
* **Maximum:** Generally 2,668 mg (4 capsules/tablets) per meal. Doses exceeding 3,000 mg of elemental calcium per day increase the risk of hypercalcemia.
## Pediatric Dosing
* **Safety/Efficacy:** Well-established guidelines for pediatric use are limited.
* **General Practice:** Dosing is individualized based on phosphate levels and elemental calcium intake. Consult a pediatric nephrologist for specific weight-based protocols.
## Dose Adjustments
* **Hypercalcemia:** If serum calcium levels exceed 10.5 mg/dL, the dose must be reduced or discontinued until calcium levels normalize.
* **Renal Impairment:** Required for ESRD patients; no adjustment needed for hepatic impairment.
## Contraindications
* Hypercalcemia.
* Hypophosphatemia.
* Nephrolithiasis (calcium-containing stones).
## Adverse Effects
* **Common:** Hypercalcemia, nausea, vomiting, constipation, and abdominal pain.
* **Serious:** Metastatic calcification (due to elevated calcium-phosphorus product >55 mg²/dL²), severe hypercalcemia.
## Key Drug Interactions
* **Fluoroquinolones/Tetracyclines:** Calcium significantly decreases the absorption of these antibiotics. Administer at least 2 hours before or 6 hours after calcium acetate.
* **Levothyroxine:** Calcium interferes with absorption; separate doses by at least 4 hours.
* **Bisphosphonates:** Decreased absorption; separate dosing by at least 2 hours.
* **Vitamin D:** Concurrent use increases the risk of hypercalcemia.
## Monitoring
* **Serum Phosphorus:** Monitor every 1–3 weeks during initial titration, then at least monthly.
* **Serum Calcium:** Monitor weekly during initial titration, then monthly.
* **Calcium-Phosphorus Product:** Keep <55 mg²/dL² to minimize the risk of vascular calcification.
## Clinical Pearls
* **Administration:** Must be taken **with meals** to be effective as a phosphate binder. If taken without food, it will not bind dietary phosphorus.
* **Comparison:** Calcium acetate is more soluble and binds more phosphorus per gram than calcium carbonate, allowing for smaller doses and potentially better adherence.
* **Supplementation:** Patients should be counseled to avoid additional calcium supplements or high-calcium vitamin D preparations to prevent hypercalcemia unless directed by a clinician.
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**Educational Disclaimer:** This information is for educational purposes only. Clinical practice protocols may vary by institution. Always verify current prescribing information, laboratory reference ranges, and local dosing guidelines via official sources such as the FDA-approved product label or trusted clinical databases (e.g., Lexicomp, UpToDate) before prescribing or administering medication.
