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# Calcium Acetate
## Overview
Calcium acetate is a phosphate binder used to reduce serum phosphate levels in patients with hyperphosphatemia, commonly associated with chronic kidney disease (CKD). It works by binding dietary phosphate in the gastrointestinal tract, forming insoluble calcium phosphate which is then excreted.
## Primary Indications
* Treatment of hyperphosphatemia in patients with end-stage renal disease (ESRD).
## Adult Dosing
* Dosing is highly individualized based on serum phosphate levels and dietary intake.
* **Starting Dose:** Typically 667 mg to 1000 mg (elemental calcium 169-254 mg) administered orally with each meal.
* **Titration:** Dose is adjusted to maintain serum phosphate below 5.5 mg/dL.
* **Maximum Dose:** No strict maximum dose, but careful monitoring of serum calcium is crucial. Doses up to 3000-4000 mg (elemental calcium 762-1016 mg) per meal are sometimes used.
## Pediatric Dosing
* Dosing in pediatric patients is not well-established and should be based on individual response and serum phosphate levels. Consultation with a pediatric nephrologist is recommended.
## Dose Adjustments
* **Renal Impairment:** Use with caution. Dosing should be guided by serum phosphate and calcium levels. Risk of hypercalcemia and vascular calcification is increased.
* **Hepatic Impairment:** No specific dose adjustment is generally required.
## Contraindications
* Hypercalcemia.
* Conditions causing hypercalcemia (e.g., metastatic bone disease, primary hyperparathyroidism).
* Ventricular fibrillation.
## Adverse Effects
* **Common:** Hypercalcemia (most significant concern), nausea, vomiting, constipation, diarrhea.
* **Serious:** Vascular calcification, soft tissue calcification, renal calculi, hypophosphatemia.
## Key Drug Interactions
* **Tetracyclines and Fluoroquinolones:** Calcium acetate can decrease the absorption of these antibiotics. Administer at least 2 hours before or 6 hours after calcium acetate.
* **Thyroid Hormones:** Calcium acetate may decrease the absorption of levothyroxine. Separate administration by at least 4 hours.
* **Antacids:** Concurrent use may increase the risk of hypercalcemia.
* **Digoxin:** Hypercalcemia from calcium acetate can increase the risk of digoxin toxicity.
## Monitoring
* **Serum Phosphate:** Monitor regularly (e.g., every 1-2 weeks initially, then monthly or as clinically indicated) to guide dosing and assess efficacy. Target is typically < 5.5 mg/dL.
* **Serum Calcium:** Monitor regularly (e.g., monthly). Target upper limit is often around 10 mg/dL, though this can vary by guideline. Episodes of hypercalcemia require dose reduction or discontinuation.
* **Intact Parathyroid Hormone (iPTH):** Monitor periodically in CKD patients.
* **Alkaline Phosphatase:** Monitor periodically.
## Clinical Pearls
* Administer with meals to maximize phosphate binding.
* Divide total daily dose among meals.
* Hypercalcemia is a critical adverse effect and requires prompt management, often involving dose reduction or discontinuation and increased fluid intake.
* In patients with CKD, calcium-based phosphate binders can contribute to calcium-phosphate product elevation, increasing the risk of calcification. Monitor the calcium-phosphate product.
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*This information is intended for educational purposes and does not substitute for professional medical advice. Always consult the most current prescribing information and clinical guidelines before making any treatment decisions.*
