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# Calcium Acetate
## Overview
Calcium acetate is a phosphate binder used primarily to manage hyperphosphatemia in patients with end-stage renal disease (ESRD). It is more efficient per milligram of elemental calcium than calcium carbonate and does not rely on gastric acidity for dissolution.
## Primary Indications
* Reduction of serum phosphorus in patients with end-stage renal disease (ESRD).
## Adult Dosing
* **Initial Dose:** 667 mg to 1,334 mg (1 to 2 capsules/tablets) orally with each meal.
* **Titration:** Adjust based on serum phosphate levels to maintain target range (typically 3.5–5.5 mg/dL).
* **Maximum Dose:** Generally titration should not exceed a total daily dose that causes hypercalcemia (>10.5 mg/dL) or a calcium-phosphate product (Ca x P) >55 mg²/dL². Common clinical practices often cap titration at 6–8 tablets daily, but specific titration must follow the managing nephrologist's protocol.
## Pediatric Dosing
* **Safety/Efficacy:** Not established in pediatric patients. Use is generally off-label and requires specialist nephrology oversight.
* **Dosing:** Often extrapolated from adult efficacy, typically initiated at 667 mg with meals and titrated strictly based on serial phosphorus and calcium monitoring.
## Dose Adjustments
* **Renal Impairment:** No adjustment required, as it is indicated for ESRD.
* **Hypercalcemia:** Reduce dose or temporarily discontinue if serum calcium exceeds upper limits.
## Contraindications
* Hypercalcemia.
* Hypophosphatemia.
* Known hypersensitivity to calcium acetate.
## Adverse Effects
* **Common:** Hypercalcemia, constipation, nausea, vomiting, abdominal pain.
* **Serious:** Metastatic calcification (associated with high calcium-phosphate product), cardiac arrhythmias (secondary to electrolyte imbalance).
## Key Drug Interactions
* **Fluoroquinolones/Tetracyclines:** Calcium significantly decreases absorption. Separate administration by at least 2–4 hours (administer antibiotic 2 hours before or 6 hours after calcium).
* **Levothyroxine:** Calcium interferes with absorption. Separate by at least 4 hours.
* **Bisphosphonates:** Calcium reduces absorption. Take at separate times of the day.
* **Digoxin:** Potential for increased risk of digitalis toxicity if hypercalcemia develops.
## Monitoring
* **Serum Phosphorus:** Every 2–4 weeks during titration.
* **Serum Calcium:** Weekly to monthly; monitor for hypercalcemia (check ionized calcium if suspicious).
* **Calcium-Phosphate Product (Ca x P):** Monitor to reduce risk of vascular calcification; target <55 mg²/dL².
## Clinical Pearls
* **Administration:** Must be taken with meals to effectively bind dietary phosphorus.
* **Comparison:** 667 mg of calcium acetate provides 169 mg of elemental calcium.
* **Vascular Safety:** Avoid use in patients with severe hypercalcemia or those with significant extra-skeletal calcification until the Ca x P product is controlled.
* **Calcium Intake:** Assess total elemental calcium intake from all sources (diet, supplements, binders) to avoid iatrogenic hypercalcemia.
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**Disclaimer:** This information is for educational purposes only. Always verify dosing, contraindications, and drug interactions against institutional protocols and the most current manufacturer-approved prescribing information or a reliable clinical database (e.g., Lexicomp, UpToDate) before prescribing or administering medication.
