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# Calcium Acetate
## Overview
Calcium acetate is a phosphate binder used to reduce serum phosphate levels in patients with chronic kidney disease (CKD) on dialysis. It binds to dietary phosphate in the gastrointestinal tract, preventing its absorption. Each 1 gram of calcium acetate contains approximately 252 mg of elemental calcium.
## Primary Indications
* Management of hyperphosphatemia in patients with end-stage renal disease (ESRD) on hemodialysis.
## Adult Dosing
* **Initial Dose:** 667 mg (2 tablets) orally with each meal.
* **Titration:** Dose should be adjusted gradually based on serum phosphate levels. The goal is to maintain serum phosphate below 6 mg/dL.
* **Maximum Dose:** Up to 4000 mg (12 tablets) per day has been studied, but higher doses increase the risk of hypercalcemia. Dosing is typically guided by serum phosphate and calcium levels, and individual patient response.
## Pediatric Dosing
* Dosing for pediatric patients is not well-established and should be guided by a nephrologist.
## Dose Adjustments
* **Hypercalcemia:** If hypercalcemia occurs, reduce the dose or temporarily discontinue. If calcium levels normalize, the dose may be cautiously reinstituted at a lower level.
* **Concomitant Calcium Intake:** Consider the total calcium load from all sources (diet, supplements, other medications).
## Contraindications
* Hypercalcemia.
* Hypersensitivity to calcium acetate.
* Severe hypercalcemia or hyperphosphatemia.
## Adverse Effects
* **Common:** Hypercalcemia, constipation, nausea, vomiting, abdominal pain, diarrhea.
* **Serious:** Cardiovascular calcification, arrhythmias, metastatic calcification.
## Key Drug Interactions
* **Tetracyclines and Quinolones:** Calcium acetate can decrease the absorption of these antibiotics by forming chelates. Administer antibiotics at least 2 hours before or 3 hours after calcium acetate.
* **Thyroid Hormones (Levothyroxine):** Calcium acetate can decrease the absorption of levothyroxine. Separate administration by at least 4 hours.
* **Biphosphonates:** Concurrent use may decrease absorption of biphosphonates. Separate administration.
* **Calcium Channel Blockers:** Monitor for potential additive effects on serum calcium.
## Monitoring
* **Serum Phosphate:** Monitor regularly (e.g., weekly or bi-weekly initially, then monthly once stable) to assess efficacy and guide dose adjustments.
* **Serum Calcium:** Monitor regularly, especially when initiating therapy or increasing the dose, to detect and manage hypercalcemia. Target serum calcium levels are generally within the normal range or slightly above, depending on institutional guidelines and patient-specific factors.
* **Intact Parathyroid Hormone (iPTH):** Monitor as indicated for management of secondary hyperparathyroidism.
* **Serum Magnesium and Phosphorus:** Monitor periodically.
## Clinical Pearls
* Administer calcium acetate with meals to maximize phosphate binding.
* Patients should be educated on signs and symptoms of hypercalcemia (e.g., nausea, vomiting, constipation, confusion, fatigue, bone pain, frequent urination).
* Consider alternative phosphate binders if adequate phosphate control is not achieved or if hypercalcemia is persistent.
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**Disclaimer:** This information is intended for clinical use and does not substitute for professional medical judgment. Always consult the most current prescribing information and institutional guidelines before administering any medication.
