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# Calcium Acetate
## Overview
Calcium acetate is a calcium salt used primarily as a phosphate binder. It provides a higher concentration of elemental calcium per gram than calcium carbonate, making it effective for binding dietary phosphorus in the gastrointestinal tract to form insoluble calcium phosphate for fecal excretion.
## Primary Indications
Hyperphosphatemia in patients with end-stage renal disease (ESRD) or chronic kidney disease (CKD) on dialysis.
## Adult Dosing
* **Initial Dose:** 667 mg to 1,334 mg (1 to 2 capsules/tablets) orally with each meal.
* **Titration:** Adjust based on serum phosphorus levels.
* **Maximum Dose:** Typically up to 3–4 tablets per meal; titrate to maintain serum phosphorus within the target range (e.g., < 5.5 mg/dL).
## Pediatric Dosing
* **Standard Dosing:** No standardized universal pediatric dose exists. Dosing is highly individualized based on serum phosphorus, calcium levels, and dietary intake.
* **Clinical Approach:** Often initiated at 800–1,668 mg/m²/day in divided doses with meals, titrated carefully under nephrology guidance.
## Dose Adjustments
* **Hypercalcemia:** If serum calcium levels exceed the target range or the patient develops hypercalcemia (> 10.5 mg/dL), the dose should be reduced or temporarily discontinued.
* **Renal Impairment:** Requires close monitoring; dosing is inherently intended for patients with renal failure.
## Contraindications
* Hypercalcemia.
* Hypophosphatemia.
* Calcium nephrolithiasis or history of calcium-containing kidney stones.
## Adverse Effects
* **Gastrointestinal:** Nausea, constipation, abdominal pain, flatulence.
* **Metabolic:** Hypercalcemia, which may manifest as confusion, lethargy, muscle weakness, or cardiac arrhythmias.
* **Vascular:** Potential for metastatic calcification with prolonged hypercalcemia and elevated calcium-phosphate product.
## Key Drug Interactions
* **Fluoroquinolones/Tetracyclines:** Calcium significantly decreases absorption. Separate administration by at least 2–4 hours.
* **Levothyroxine:** Calcium interferes with absorption. Separate by at least 4 hours.
* **Bisphosphonates:** Reduces absorption. Space by at least 2 hours.
* **Vitamin D:** Concurrent use increases risk of hypercalcemia.
## Monitoring
* **Serum Phosphorus:** Every 2–4 weeks initially, then periodically once stable.
* **Serum Calcium:** Monitor frequently during titration to prevent hypercalcemia.
* **Calcium-Phosphate Product:** Aim to keep < 55 mg²/dL² to minimize the risk of vascular calcification.
## Clinical Pearls
* **Timing:** Must be taken **with meals** to effectively bind dietary phosphorus. If a snack is not taken, the medication provides no phosphate-binding benefit.
* **Elemental Calcium:** 667 mg of calcium acetate provides approximately 169 mg of elemental calcium.
* **Formulation Warning:** Do not substitute with calcium citrate or carbonate without dose conversion, as phosphate-binding efficacy differs.
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**Educational Disclaimer:** This information is for educational purposes only. Always verify dosing, contraindications, and drug interactions with current, institution-approved prescribing references or pharmaceutical databases before clinical administration.
