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# Calcium Acetate
## Overview
Calcium acetate is a calcium salt used primarily as a phosphate binder. It provides higher elemental calcium content per weight and greater phosphate-binding capacity compared to calcium carbonate, especially in patients with an elevated gastric pH.
## 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. Most patients require 2–4 capsules per meal to achieve target phosphorus levels.
* **Maximum Dose:** Typically capped by the development of hypercalcemia; doses exceeding 10–12 grams daily are generally avoided.
* *Note: Dosing is highly dependent on local nephrology protocols and individual baseline calcium levels.*
## Pediatric Dosing
* **Dosing:** Not well-established. Generally range from 500–1,000 mg per meal, titrated to effect.
* *Consult current pediatric institutional protocols or a pediatric nephrologist before prescribing due to the high risk of iatrogenic hypercalcemia.*
## Dose Adjustments
* **Renal Impairment:** No specific adjustment required; it is designed for this population. Monitor serum calcium and phosphorus closely.
* **Hypercalcemia:** If calcium levels rise above the upper limit of normal, reduce the dose or switch to a non-calcium-based phosphate binder (e.g., sevelamer or lanthanum).
## Contraindications
* Hypercalcemia.
* Hypophosphatemia.
* Recent history of calcium-based nephrolithiasis.
## Adverse Effects
* **Gastrointestinal:** Nausea, constipation, abdominal pain, diarrhea.
* **Metabolic:** Hypercalcemia (symptoms include nausea, vomiting, confusion, polydipsia, and cardiac arrhythmias).
* **Vascular:** Potential for increased vascular calcification with prolonged high-dose calcium-based binder use.
## Key Drug Interactions
* **Fluoroquinolones/Tetracyclines:** Calcium significantly reduces absorption. Administer antibiotics 2 hours before or 6 hours after calcium acetate.
* **Levothyroxine:** Calcium interferes with absorption. Separate administration by at least 4 hours.
* **Bisphosphonates:** Calcium reduces bisphosphonate absorption; avoid close co-administration.
* **Corticosteroids:** May decrease calcium absorption.
## Monitoring
* **Serum Phosphorus:** Monitor every 2–4 weeks during initiation/titration, then periodically.
* **Serum Calcium:** Monitor weekly during initiation; frequent monitoring is essential to avoid hypercalcemia.
* **Calcium-Phosphorus Product:** Aim for < 55 mg²/dL² to minimize the risk of metastatic calcification.
## Clinical Pearls
* **Administration:** Must be taken **with meals** to effectively bind dietary phosphorus.
* **Dosing Form:** 667 mg of calcium acetate provides approximately 169 mg (8.45 mEq) of elemental calcium.
* **Safety:** Patients should be warned not to use over-the-counter calcium supplements or Vitamin D analogs unless directed, due to the high risk of additive hypercalcemia.
* **Superiority:** Calcium acetate is more effective at binding phosphate in the gut than calcium carbonate because it is more soluble across the pH spectrum of the GI tract.
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**Disclaimer:** This information is for educational purposes and does not substitute for professional medical judgment. Always verify current prescribing information, institutional guidelines, and patient-specific factors before prescribing or administering medication.
