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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 works by binding to dietary phosphate in the gastrointestinal tract, preventing its absorption.
## Primary Indications
* Management of hyperphosphatemia in patients with end-stage renal disease (ESRD).
## Adult Dosing
* **Initial dose:** 2 tablets orally with each meal.
* **Titration:** Increase dose gradually based on serum phosphate levels. Doses can range from 2 to 8 tablets per meal, taken with meals and snacks.
* **Maximum dose:** Typically 8-16 tablets per day, but may be individualized. Doses higher than 16 tablets per day are generally not recommended due to the risk of hypercalcemia and exceeding acetate load.
## Pediatric Dosing
* Dosing is not well established in pediatric patients. Consultation with a pediatric nephrologist is recommended. Some sources suggest starting at 10-12 mg/kg/day of elemental calcium, divided into 3-4 doses with meals.
## Dose Adjustments
* **Renal Impairment:** Dose should be carefully titrated based on serum calcium, phosphate, and intact parathyroid hormone (iPTH) levels. Patients with CKD are at increased risk of hypercalcemia.
* **Hepatic Impairment:** No specific dose adjustments are typically required, but monitoring is essential.
## Contraindications
* Hypercalcemia.
* Hypersensitivity to calcium acetate or any component of the formulation.
* Patients with hypercalcemia or conditions that predispose to hypercalcemia (e.g., metastatic bone disease, certain malignancies).
## Adverse Effects
* **Common:** Hypercalcemia (symptoms include constipation, nausea, vomiting, abdominal pain, polyuria, polydipsia, confusion, fatigue, arrhythmias), hypophosphatemia.
* **Less Common:** Gastrointestinal upset (dyspepsia, diarrhea), headache.
## 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.
* **Thyroid Hormones:** Calcium acetate can decrease the absorption of levothyroxine. Separate administration by at least 4 hours.
* **Bisphosphonates:** May reduce the absorption of bisphosphonates. Separate administration by at least 2 hours.
* **Calcium Channel Blockers:** Potential for additive hypercalcemia.
* **Fat-soluble Vitamins:** May decrease absorption.
## Monitoring
* **Serum Calcium:** Regularly monitor serum calcium levels, especially at initiation and dose adjustments. Aim to keep calcium within the desired range (e.g., below 10.5 mg/dL or as per institutional guidelines).
* **Serum Phosphate:** Monitor phosphate levels to assess efficacy.
* **Intact Parathyroid Hormone (iPTH):** Monitor for appropriate suppression in CKD patients.
* **Serum Magnesium and Alkaline Phosphatase:** May be helpful in assessing calcium-metabolism status.
## Clinical Pearls
* Administer calcium acetate with meals and snacks to effectively bind dietary phosphate.
* Educate patients on the signs and symptoms of hypercalcemia.
* Consider the total elemental calcium load when prescribing; each 667 mg tablet of calcium acetate contains approximately 169 mg of elemental calcium.
* For patients also receiving calcium supplements or vitamin D analogs, careful monitoring for hypercalcemia is crucial.
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*This information is intended for healthcare professionals. Always consult the current prescribing information and institutional guidelines for complete details and to confirm recommendations.*
