Calcium Acetate

# Calcium acetate ## Overview - **Classification**: Phosphate binder - **Mechanism**: Binds to dietary phosphate in the gastrointestinal tract to form insoluble calcium phosphate, which is then excreted in feces, reducing phosphate absorption. ## Primary Indications 1. **Hyperphosphatemia in End-Stage Renal Disease (ESRD)** - Management of elevated serum phosphorus levels in patients undergoing dialysis. ## Adult Dosing ### Standard Dosing **Hyperphosphatemia in ESRD** - **Dose**: Initially **667 mg** (1 capsule) - **Frequency**: **3 times daily** - **Route**: Oral, with each meal - **Duration**: Ongoing, as long as hyperphosphatemia persists in ESRD - **Maximum**: Doses should be adjusted to achieve target serum phosphorus levels. Typical daily dose is **2-4 grams/day**. Some patients may require up to **2000-3340 mg** with each meal. ### Dose Adjustments - **Renal Impairment**: Used specifically in ESRD; dose is titrated based on serum phosphorus levels, not CrCl. - **Hepatic Impairment**: No specific dose adjustments required. - **Elderly Patients**: No specific dose adjustments required beyond standard adult dosing. Monitor for signs of hypercalcemia. ## Pediatric Dosing *Safety and efficacy not well-established in pediatric patients. Dosing is highly individualized based on serum phosphorus levels and often considered off-label.* ### Neonates (0-28 days) - **Dose**: Not routinely recommended. If used, consult a nephrologist. - **Special Notes**: Limited data. Monitor closely for hypercalcemia. ### Infants (1-12 months) - **Dose**: Initial dose typically **50-155 mg/kg/day** - **Frequency**: Divided into **3-4 doses** with meals - **Maximum**: Titrate based on phosphorus levels. Maximize calcium intake from all sources to avoid hypercalcemia. ### Children (1-12 years) - **Dose**: Initial dose typically **50-155 mg/kg/day** - **Frequency**: Divided into **3-4 doses** with meals - **Maximum**: Do not exceed adult maximum daily dose of **2-4 grams/day**. Adjust based on phosphorus levels. ### Adolescents (13-18 years) - **Dose**: Start with adult initial dose of **667 mg** - **Frequency**: **3 times daily** with meals - **Maximum**: Adult maximum daily dose of **2-4 grams/day**. Titrate to phosphorus levels. ## Safety Information ### Contraindications - **Absolute**: Hypercalcemia (serum calcium > 10.5 mg/dL) - **Absolute**: Hypophosphatemia - **Absolute**: Known hypersensitivity to calcium acetate or any component ### Common Adverse Effects - **Very Common (>10%)**: Nausea, vomiting, constipation, diarrhea - **Common (1-10%)**: Abdominal pain - **Serious but Rare**: Hypercalcemia (especially with over-dosing or concomitant Vitamin D), calciphylaxis (associated with high calcium-phosphate product). ### Key Drug Interactions - **Tetracyclines/Fluoroquinolones**: Decreased absorption of antibiotics. Separate administration by **1-3 hours** before or **3-6 hours** after calcium acetate. - **Bisphosphonates**: Decreased absorption. Administer **30-60 minutes** before or **2-4 hours** after calcium acetate. - **Thyroid Hormones (e.g., Levothyroxine)**: Decreased absorption. Separate by at least **4 hours**. - **Vitamin D analogs (e.g., calcitriol)**: Increased risk of hypercalcemia. Monitor serum calcium closely. - **Iron supplements**: Decreased iron absorption. Separate by **2-3 hours**. ## Monitoring & Follow-up - **Before Treatment**: Baseline serum phosphorus, calcium (total and ionized), albumin, PTH (parathyroid hormone). - **During Treatment**: Serum phosphorus and calcium levels (total and ionized) should be monitored **weekly-monthly** initially, then **monthly-quarterly** once stable. - **Clinical Signs**: Monitor for signs of hypercalcemia (constipation, nausea, fatigue, confusion, arrhythmias) and hypophosphatemia (muscle weakness, paresthesias). ## Clinical Pearls - 💡 **Timing is crucial**: Must be taken **with meals** (or within 15 minutes of starting a meal) to effectively bind dietary phosphate. - 💡 **Dose titration**: Dose is highly individualized and titrated to achieve target serum phosphorus levels, typically **2.5-4.5 mg/dL** in ESRD patients. - 💡 **Not elemental calcium**: The listed dose (e.g., **667 mg**) refers to calcium acetate salt, not elemental calcium. - 💡 **Monitor Ca x PO4 product**: Keep the serum calcium-phosphate product **<55 mg²/dL²** to reduce the risk of soft tissue and vascular calcification. - 💡 **Formulation**: Available in capsules and often as a chewable tablet (e.g., PhosLo Gelcaps). > **⚠️ Important**: This information is for educational purposes only. Always consult current prescribing information, local guidelines, and clinical judgment before prescribing.