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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 soluble and binds dietary phosphate in the gastrointestinal tract to form insoluble calcium phosphate, which is then excreted in feces.
## Primary Indications
* Reduction of serum phosphorus in patients with end-stage renal disease (ESRD).
## Adult Dosing
* **Initial Dose:** 2 capsules (1334 mg calcium acetate) with each meal.
* **Titration:** Adjust based on serum phosphate levels.
* **Goal:** Maintain serum phosphorus within the target range (typically < 5.5 mg/dL).
* **Maximum Dose:** Highly individualized; most clinicians rarely exceed 3–4 capsules per meal due to the risk of hypercalcemia.
## Pediatric Dosing
* **Safety/Efficacy:** Well-established dosing is not standard and varies significantly by center.
* **Typical Starting Range:** 500–1000 mg/m²/day in divided doses with meals, titrated to effect.
* **Caution:** Consult local pediatric nephrology protocols as hypercalcemia risk is high in children.
## Dose Adjustments
* **Renal Impairment:** No renal dosage adjustment required; this is the target population.
* **Hepatic Impairment:** No adjustment required.
* **Hypercalcemia:** If serum calcium levels rise or phosphorus reaches target, decrease dose or discontinue.
## Contraindications
* Hypercalcemia.
* Hypophosphatemia.
* Known hypersensitivity to any component of the formulation.
## Adverse Effects
* **Common:** Nausea, constipation, diarrhea, vomiting.
* **Serious:** Hypercalcemia (symptoms: lethargy, confusion, cardiac arrhythmias), metastatic calcification (soft tissue/vascular).
## Key Drug Interactions
* **Quinolones/Tetracyclines:** Calcium acetate significantly decreases oral absorption. Separate doses by at least 2–4 hours.
* **Levothyroxine:** Calcium binds levothyroxine; separate administration by at least 4 hours.
* **Bisphosphonates:** Calcium may decrease oral absorption; space doses by 2 hours.
* **Calcium Supplements:** Avoid concurrent use of other calcium-based supplements/antacids to prevent hypercalcemia.
## Monitoring
* **Serum Phosphorus:** Baseline and at least monthly during initiation/titration.
* **Serum Calcium:** Monitor weekly initially, then monthly.
* **Calcium-Phosphorus Product:** Keep < 55 mg²/dL² to reduce the risk of metastatic calcification.
## Clinical Pearls
* **Administration:** Must be taken **with meals** to be effective as a phosphate binder.
* **Calcium Content:** 667 mg of calcium acetate contains 169 mg of elemental calcium.
* **Superiority:** Calcium acetate has a higher binding capacity for phosphate compared to calcium carbonate, especially in patients with low gastric acidity.
* **Hypercalcemia Risk:** Patients on chronic dialysis who develop severe hypercalcemia may require a switch to a non-calcium-based phosphate binder (e.g., sevelamer, lanthanum).
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**Educational Disclaimer:** This information is for educational purposes only. Drug dosing, contraindications, and interaction profiles can change. Always verify specific doses and clinical protocols against current institutional guidelines, the package insert, or professional resources like Lexicomp or Micromedex before prescribing or administering medication.
