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## Calcium Acetate
### Overview
Calcium acetate is a phosphate binder used to control hyperphosphatemia in patients with chronic kidney disease (CKD). It binds to dietary phosphate in the gastrointestinal tract, forming insoluble calcium phosphate, which is then excreted in the feces.
### Primary Indications
* Treatment of hyperphosphatemia in patients with end-stage renal disease (ESRD).
### Adult Dosing
* **Initial Dose:** 667 mg (equivalent to 13.3 mEq elemental calcium and 13.3 mEq acetate) orally three times daily with meals.
* **Titration:** Doses should be adjusted based on serum phosphate levels. Typical maintenance doses range from 1334 mg to 2001 mg orally three times daily with meals.
* **Maximum Dose:** While no strict maximum dose is established, doses exceeding 10 g daily are generally not recommended due to the risk of hypercalcemia and potential for aluminum toxicity if used concurrently with aluminum-containing antacids.
### Pediatric Dosing
* Specific dosing in pediatric patients is not well-established and should be determined by a nephrologist. However, some sources suggest starting doses of 10-20 mg/kg/day of elemental calcium divided into 3 doses with meals, titrated to control serum phosphate.
### Dose Adjustments
* **Renal Impairment:** Dose adjustment is based on serum phosphate and calcium levels. In patients with CKD, careful monitoring is crucial.
* **Hypercalcemia:** If serum calcium exceeds the upper limit of normal (typically 10.5 mg/dL or 2.62 mmol/L), reduce the dose or temporarily discontinue.
### Contraindications
* Hypercalcemia.
* Hypersensitivity to calcium acetate.
* Concomitant use with IV calcium salts.
### Adverse Effects
* **Common:** Hypercalcemia, hypophosphatemia, nausea, vomiting, constipation, diarrhea.
* **Serious:** Cardiovascular events (arrhythmias, ECG changes) due to hypercalcemia, aluminum toxicity (if used with aluminum-containing products).
### Key Drug Interactions
* **Tetracyclines and Fluoroquinolones:** Calcium acetate can decrease the absorption of these antibiotics. Administer at least 1 hour before or 3 hours after calcium acetate.
* **Thyroid Hormones (Levothyroxine):** Calcium acetate can reduce the absorption of levothyroxine. Administer levothyroxine at least 4 hours before or 4 hours after calcium acetate.
* **Antacids:** Concurrent use of non-calcium-based antacids may increase the risk of hypercalcemia.
### Monitoring
* **Serum Phosphate:** Monitor frequently (e.g., weekly) until target levels are achieved, then monitor periodically. Target serum phosphate levels are generally less than 5.5 mg/dL (1.78 mmol/L).
* **Serum Calcium:** Monitor frequently, especially during dose titration and in patients with a history of hypercalcemia.
* **Alkaline Phosphatase:** Monitor periodically.
* **Bicarbonate:** Monitor periodically, as acetate is metabolized to bicarbonate.
### Clinical Pearls
* Calcium acetate is generally preferred over calcium carbonate for phosphate binding in ESRD patients due to lower elemental calcium content per dose and less calcium absorption.
* Administer calcium acetate with meals to maximize phosphate binding.
* Encourage adequate fluid intake to help prevent constipation.
* Educate patients on symptoms of hypercalcemia (e.g., nausea, vomiting, constipation, confusion, fatigue, frequent urination).
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*Disclaimer: This information is intended for healthcare professionals. Always consult the most current prescribing information and relevant guidelines before making clinical decisions.*
