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# Calcium Acetate
## Overview
Calcium acetate is a phosphate binder used to reduce serum phosphorus levels in patients with end-stage renal disease (ESRD). It is highly soluble and provides more elemental calcium per gram of salt compared to calcium carbonate, allowing for effective binding of dietary phosphate in the gastrointestinal tract.
## Primary Indications
* Reduction of serum phosphorus in patients with end-stage renal disease (ESRD).
## Adult Dosing
* **Initial Dose:** 1,334 mg (two 667 mg capsules/tablets) orally with each meal.
* **Titration:** Adjust based on serum phosphate levels.
* **Maximum:** Typically 3,000 mg to 4,000 mg of elemental calcium per day from all sources, though clinical protocols vary widely based on hypercalcemia risk. Titrate to target serum phosphorus levels (typically 3.5–5.5 mg/dL).
## Pediatric Dosing
* **Safety and Efficacy:** Not established in pediatric patients. Use is off-label and requires nephrology guidance.
* **Dosing:** Start with 15–30 mg/kg/day (calculated as calcium acetate) divided with meals, titrated to effect. High risk of hypercalcemia requires frequent laboratory monitoring.
## Dose Adjustments
* **Hypercalcemia:** If serum calcium levels exceed 10.5 mg/dL, decrease or discontinue the dosage.
* **Renal Impairment:** Required in ESRD patients; no adjustment needed for dosage form, but frequency is tied strictly to meal intake.
## Contraindications
* Hypercalcemia.
* Hypophosphatemia.
* Nephrolithiasis (calcium-containing stones).
## Adverse Effects
* **Common:** Hypercalcemia, constipation, nausea, vomiting.
* **Serious:** Metastatic calcification (due to elevated calcium-phosphorus product), adynamic bone disease.
## Key Drug Interactions
* **Fluoroquinolones/Tetracyclines:** Calcium acetate significantly reduces antibiotic absorption. Separate administration by at least 2 hours.
* **Levothyroxine:** Calcium interferes with absorption. Separate by at least 4 hours.
* **Bisphosphonates:** Reduces absorption. Separate by at least 2 hours.
* **Iron Supplements:** Concurrent use reduces iron absorption; separate by 2–4 hours.
## Monitoring
* **Serum Phosphorus:** Monitor every 1–3 weeks during dose titration, then monthly or quarterly.
* **Serum Calcium:** Check weekly initially, then monthly.
* **Calcium-Phosphorus Product:** Keep below 55 mg²/dL² to minimize the risk of soft tissue calcification.
## Clinical Pearls
* **Efficacy:** Effectiveness is dependent on taking the medication **with meals** to ensure it binds dietary phosphorus before absorption.
* **Choice of Binder:** Calcium acetate is preferred over calcium carbonate in renal patients because it is more soluble at higher gastric pH levels and has a higher binding capacity per milligram.
* **Patient Education:** Advise patients that missed doses are missed opportunities for phosphate binding; do not "catch up" by doubling doses.
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**Disclaimer:** This information is for educational purposes only. Always consult current institutional protocols and the most recent FDA-approved prescribing information (package insert) before prescribing or administering medication. Verify all patient-specific allergies and drug-drug interactions using a validated clinical decision support tool.
