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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 gram than calcium carbonate and demonstrates higher phosphate-binding efficiency in the acidic environment of the stomach.
## Primary Indications
* Reduction of serum phosphorus in patients with end-stage renal disease (ESRD).
* Treatment/prevention of calcium deficiency (off-label use, though carbonate is more common).
## Adult Dosing
* **Hyperphosphatemia:** Initial dose is 1,334 mg (two 667 mg capsules/tablets) orally with each meal.
* **Titration:** Increase dose gradually based on serum phosphate levels to achieve target goal (typically < 5.5 mg/dL).
* **Maximum:** Doses exceeding 12 tablets/day are rarely required; local protocol and serum calcium monitoring must dictate upper limits to prevent hypercalcemia.
## Pediatric Dosing
* **Established Dosing:** Use is generally guided by pediatric nephrology protocols.
* **Initial:** Typical starting dose is 20–30 mg/kg/day of elemental calcium divided with meals, adjusted based on serum phosphate and calcium levels.
* **Caution:** Pediatric patients require strict monitoring due to the risk of hypercalcemia interfering with bone growth and development. Always verify with institutional pediatric guidelines.
## Dose Adjustments
* **Renal Impairment:** No specific adjustment required for renal insufficiency, but monitoring frequency must be increased.
* **Hypercalcemia:** If pre-dose serum calcium exceeds 10.5 mg/dL or if symptoms of hypercalcemia occur, decrease or temporarily discontinue dose.
## Contraindications
* Hypercalcemia.
* Hypophosphatemia.
* Nephrolithiasis (calcium-containing stones).
## Adverse Effects
* **Common:** Hypercalcemia, nausea, vomiting, constipation, and abdominal pain.
* **Serious:** Soft tissue calcification (metastatic calcification), cardiac arrhythmias (severe hypercalcemia).
## Key Drug Interactions
* **Fluoroquinolones/Tetracyclines:** Reduced absorption of these antibiotics; administer calcium acetate at least 2 hours before or 6 hours after these medications.
* **Levothyroxine:** Calcium interferes with absorption; administer at least 4 hours apart.
* **Bisphosphonates:** Reduced absorption; separate doses by at least 2 hours.
* **Calcium Channel Blockers:** Potential for reduced efficacy of the CCB in the presence of severe hypercalcemia.
## Monitoring
* **Serum Phosphorus:** Monitor weekly during initiation and dose titration; then periodically.
* **Serum Calcium:** Monitor weekly initially; avoid exceeding the product of calcium x phosphorus (Ca × P) > 55 mg²/dL² to minimize risks of metastatic calcification.
* **Symptoms of Hypercalcemia:** Monitor for confusion, lethargy, muscle weakness, and cardiac rhythm changes.
## Clinical Pearls
* **Administration:** Must be taken **with meals** to effectively bind dietary phosphate. If a meal is missed, the calcium acetate dose should also be skipped.
* **Compliance:** The high pill burden associated with phosphate binders often leads to poor adherence.
* **Comparison:** Calcium acetate binds approximately 45% more phosphate than calcium carbonate on an elemental calcium basis.
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*Educational Disclaimer: This information is for educational purposes and does not substitute for professional medical judgment. Always verify current prescribing information, institutional protocols, and patient-specific factors before administering medication.*
