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# Calcium Acetate
## Overview
Calcium acetate is a phosphate binder used to reduce serum phosphorus levels in patients with hyperphosphatemia, primarily those with end-stage renal disease (ESRD). It works by binding to dietary phosphate in the gastrointestinal tract, forming insoluble calcium phosphate which is then excreted in the feces.
## Primary Indications
* Hyperphosphatemia in patients with chronic kidney disease (CKD) on dialysis.
## Adult Dosing
* **Initial Dose:** 667 mg to 1333 mg (approximately 1.3 to 2.6 mEq of calcium) taken orally with each meal.
* **Titration:** Dosage should be individualized based on serum phosphorus levels.
* **Maximum Recommended Dose:** Typically up to 1333 mg per dose (or 4000 mg/day total for some formulations). However, the total daily dose should not exceed the amount necessary to control serum phosphorus, and the total elemental calcium intake (from all sources) should be monitored.
## Pediatric Dosing
* Data is limited and dosing is typically individualized based on patient weight and serum phosphorus levels. Consultation with a pediatric nephrologist is recommended. Some sources suggest initial doses of 10-20 mg/kg/day of elemental calcium divided into 3 doses with meals, but this requires careful monitoring and adjustment.
## Dose Adjustments
* **Renal Impairment:** Dosing is specifically for patients with CKD. Careful monitoring of serum calcium and phosphorus is crucial.
* **Hypercalcemia:** If hypercalcemia occurs, the dose should be reduced or temporarily discontinued.
## Contraindications
* Hypercalcemia.
* Hypersensitivity to calcium acetate.
* Patients with significantly elevated serum calcium levels.
## Adverse Effects
* **Common:** Hypercalcemia, constipation, nausea, vomiting, diarrhea, abdominal pain.
* **Serious:** Calcification of soft tissues (vascular calcification), kidney stones, hypophosphatemia.
## Key Drug Interactions
* **Tetracyclines and Quinolones:** Calcium acetate can decrease the absorption of these antibiotics by forming chelates. Administer oral tetracyclines and quinolones at least 2 hours before or 6 hours after calcium acetate.
* **Digoxin:** Hypercalcemia can increase the risk of digoxin toxicity.
* **Iron Supplements:** Calcium may interfere with iron absorption.
* **Levothyroxine:** Calcium acetate may decrease the absorption of levothyroxine. Separate administration by at least 4 hours.
* **Thiazide Diuretics:** May increase the risk of hypercalcemia.
## Monitoring
* **Serum Phosphorus:** Monitor regularly to assess efficacy and guide dosing.
* **Serum Calcium:** Monitor regularly to detect and prevent hypercalcemia. Target serum calcium levels are typically within the normal range.
* **Serum Magnesium and Alkaline Phosphatase:** May be monitored periodically.
* **Signs and symptoms of hypercalcemia:** Bone pain, abdominal pain, constipation, confusion, nausea, polyuria, polydipsia.
## Clinical Pearls
* Administer calcium acetate with meals to maximize phosphate binding.
* Total daily calcium intake from all sources (medications, diet, supplements) should be considered to avoid exceeding recommended limits and to prevent hypercalcemia.
* The goal is to reduce serum phosphorus to the target range, often < 5.5 mg/dL, but this can vary based on individual patient goals and guidelines.
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*This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional guidelines for complete details.*
