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# Calcium Acetate
## Overview
Calcium acetate is a calcium salt used primarily as a phosphate binder in patients with end-stage renal disease (ESRD). It is more effective at binding dietary phosphate per milligram of elemental calcium compared to calcium carbonate and is less likely to contribute to systemic hypercalcemia if adjusted correctly, though this risk remains significant.
## Primary Indications
* Reduction of serum phosphorus in patients with hyperphosphatemia associated with chronic kidney disease (CKD/ESRD).
## Adult Dosing
* **Initial Dose:** 2 capsules or 667 mg tablet with each meal.
* **Titration:** Adjust based on serum phosphate levels to target a goal typically < 5.5 mg/dL.
* **Maximum:** Dosing is often titrated up to 3–4 capsules/tablets per meal depending on the phosphate content of the meal and clinical response.
## Pediatric Dosing
Safety and efficacy have not been established in pediatric patients. Use is off-label and requires nephrology consultation. Dosing is typically individualized based on serum phosphate levels and dietary daily intake.
## Dose Adjustments
* **Renal Impairment:** Required for all patients on dialysis.
* **Hypercalcemia:** If serum calcium levels exceed 10.5–11.0 mg/dL, the dose must be reduced or discontinued immediately.
## Contraindications
* Hypercalcemia.
* Hypophosphatemia.
* Renal stones (calcium-based).
## Adverse Effects
* **Common:** Nausea, vomiting, abdominal pain, constipation.
* **Serious:** Hypercalcemia (manifesting as malaise, confusion, cardiac arrhythmias), soft tissue calcification (with prolonged elevated Calcium x Phosphorus product).
## Key Drug Interactions
* **Quinolones and Tetracyclines:** Calcium significantly decreases absorption. Separate administration by at least 2 hours before or 6 hours after calcium acetate.
* **Levothyroxine:** Calcium interferes with absorption. Separate by at least 4 hours.
* **Bisphosphonates:** Calcium reduces absorption; separate doses significantly.
## Monitoring
* **Serum Phosphorus:** Monitor every 1–3 weeks during dose titration, then monthly to quarterly.
* **Serum Calcium:** Monitor weekly during initiation and dose titration.
* **Calcium-Phosphate Product:** Maintain < 55 mg²/dL² to minimize the risk of metastatic calcification.
## Clinical Pearls
* **Administration:** Must be taken with meals to bind dietary phosphate. Taking it on an empty stomach does not effectively lower serum inorganic phosphate.
* **Composition:** 667 mg of calcium acetate contains 169 mg (approximately 8.45 mEq) of elemental calcium.
* **Superiority:** Calcium acetate has approximately twice the phosphate-binding capacity of calcium carbonate due to higher solubility in the upper GI tract.
* **Adherence:** Pill burden is a significant barrier to compliance in ESRD patients; evaluate the patient's diet and adherence if phosphate targets are not met before simply increasing the dose.
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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.*
