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# Calcium Acetate
## Overview
Calcium acetate is a calcium salt used primarily as a phosphate binder. It provides higher elemental calcium per gram compared to calcium carbonate, allowing for effective phosphate binding with lower total elemental calcium intake.
## Primary Indications
* Reduction of serum phosphorus in patients with end-stage renal disease (ESRD).
* Hypocalcemia (off-label use, though usually inferior to calcium gluconate/carbonate for this purpose).
## Adult Dosing
* **Hyperphosphatemia:** 1,334 mg (2 capsules/tablets) with each meal.
* **Titration:** Adjust based on serum phosphate levels; common clinical titration increases to 2,668 mg with larger meals. Maximum dose typically does not exceed 12 g/day (approx. 3,000 mg elemental calcium) to avoid hypercalcemia.
## Pediatric Dosing
* **Hyperphosphatemia:** No standardized FDA-approved dosing. Dosing is highly variable and depends on institutional protocols/nephrology guidance.
* **Typical initiation:** Often ranges from 500–1,000 mg per meal, titrated to serum phosphorus targets.
## Dose Adjustments
* **Renal Impairment:** Required dose is based on serum phosphorus response. Monitor closely for hypercalcemia if total elemental calcium intake is high.
* **Hypercalcemia:** Reduce dose or switch to a non-calcium-based binder (e.g., sevelamer or lanthanum).
## Contraindications
* Hypercalcemia.
* Hypophosphatemia (during treatment of hyperphosphatemia).
* Renal calculi (calcium-based stones).
## Adverse Effects
* **Gastrointestinal:** Constipation, nausea, vomiting, abdominal pain.
* **Metabolic:** Hypercalcemia (symptoms include confusion, lethargy, anorexia, polyuria, cardiac arrhythmias).
* **Vascular:** Potential for metastatic calcification if the calcium-phosphorus product exceeds 55 mg²/dL².
## Key Drug Interactions
* **Quinolones/Tetracyclines:** Calcium significantly reduces absorption. Administer at least 2 hours before or 6 hours after these antibiotics.
* **Bisphosphonates:** Calcium reduces absorption; stagger doses by at least 2 hours.
* **Levothyroxine:** Space by at least 4 hours to avoid chelation.
* **Iron Salts:** Calcium decreases iron absorption; separate doses by 2 hours.
## Monitoring
* **Serum Phosphorus:** Target depends on clinical guidelines (e.g., KDOQI/KDIGO).
* **Serum Calcium:** Monitor initially and during titration to avoid hypercalcemia.
* **Calcium-Phosphorus (Ca x P) Product:** Should be kept <55 mg²/dL² to minimize the risk of soft tissue calcification.
## Clinical Pearls
* **Timing is critical:** Calcium acetate MUST be taken with food to effectively bind dietary phosphorus. It is ineffective if taken between meals.
* **Elemental Calcium:** 668 mg of calcium acetate contains 169 mg of elemental calcium.
* **Patient Education:** Emphasize that this medication is a phosphate binder, not a calcium supplement. If a meal is skipped, the dose should not be taken.
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*Disclaimer: This information is for educational purposes only. Always consult current institutional guidelines, product monographs, or clinical pharmacists before prescribing or administering medication.*
