CALCIUM ACETATE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for CALCIUM ACETATE (CALCIUM ACETATE).
Calcium acetate binds with dietary phosphate in the gastrointestinal tract, forming insoluble calcium phosphate that is excreted in feces, thereby reducing serum phosphate levels.
| Metabolism | Not metabolized; minimally absorbed from the GI tract. |
| Excretion | Calcium acetate dissociates in the gastrointestinal tract; calcium is absorbed or excreted in feces, acetate is metabolized. Renal excretion accounts for <20% of absorbed calcium; biliary/fecal elimination is minimal. Unabsorbed calcium acetate is eliminated in feces. |
| Half-life | Not applicable for calcium acetate as a compound; serum calcium half-life is approximately 4–6 hours after absorption, reflecting rapid redistribution and renal clearance. |
| Protein binding | Calcium: ~40% bound to albumin and other plasma proteins; calcium acetate itself does not bind. |
| Volume of Distribution | Calcium: 0.3–0.5 L/kg for total body calcium; the clinically relevant Vd for absorbed calcium approximates extracellular fluid volume (~0.2 L/kg). |
| Bioavailability | Oral: Absorption of elemental calcium is ~30–40% under fasting conditions; decreases with food. Calcium acetate provides ~21% elemental calcium. |
| Onset of Action | Oral: Reduction in serum phosphate begins within 2–4 hours; maximal phosphate binding occurs at 4–6 hours post-dose. |
| Duration of Action | Phosphate binding effect persists for 4–6 hours after oral administration; requires dosing with meals for sustained effect. |
| Molecular Weight | 158.17 |
668 mg (169 mg calcium) to 2 g (500 mg calcium) orally three times daily with meals, titrated to maintain serum phosphorus within target range (2.5-4.5 mg/dL). Maximum dose typically 4 g calcium per day.
| Dosage form | CAPSULE |
| Renal impairment | Dose is based on serum phosphorus levels and dialysis status. No specific GFR-based dose adjustment; contraindicated in severe hypercalcemia. For hemodialysis patients, titrate to maintain phosphorus levels 3.5-5.5 mg/dL. |
| Liver impairment | No dose adjustment required for hepatic impairment. |
| Pediatric use | Children: 50-100 mg/kg/day (as calcium acetate) orally in divided doses with meals, adjusted to maintain serum phosphorus within age-appropriate normal range. Maximum 4 g calcium acetate per day. |
| Geriatric use | Start at lower end of dosing range (e.g., 667 mg with meals) and titrate slowly; monitor serum calcium and phosphorus levels closely due to increased risk of hypercalcemia and constipation. |
| 1st trimester | Use only if clearly needed. No known teratogenicity; calcium acetate is a normal constituent of bone. However, hypercalcemia may occur, which could be detrimental. |
| 2nd trimester | Use with caution; monitor maternal serum calcium levels to avoid hypercalcemia, which may affect fetal skeletal development. |
| 3rd trimester | Use with caution; excessive calcium may cause maternal hypercalcemia, potentially leading to fetal hypoparathyroidism or other complications. |
Clinical note
Comprehensive clinical and safety monograph for CALCIUM ACETATE (CALCIUM ACETATE).
| Placental transfer | Calcium ions cross the placenta actively, but calcium acetate itself does not; any effect is via increased maternal calcium levels. |
| Breastfeeding | Calcium acetate is not significantly absorbed systemically; however, it can increase maternal serum calcium levels. Monitor infant for signs of hypercalcemia (e.g., constipation, irritability). Generally considered compatible with breastfeeding if maternal levels are controlled. |
■ FDA Black Box Warning
None
| Serious Effects |
HypercalcemiaHypersensitivity to calcium acetate or any componentSevere renal impairment with risk of hypercalcemia (relative contraindication; use with caution)
| Precautions | Monitor serum calcium levels to avoid hypercalcemia, Risk of hypercalcemia in patients on vitamin D analogs or thiazide diuretics, Use with caution in patients with hypercalcemia, hypoparathyroidism, or renal stones |
| Food/Dietary | Take with meals to bind dietary phosphate. Avoid high-phosphate foods (e.g., dairy, nuts, colas, processed meats) unless otherwise directed. Separate from iron supplements or thyroid medications by at least 1 hour. Do not consume large amounts of calcium-fortified foods or beverages without medical advice. |
Loading safety data…
| Lactation Rating | L2 (Limited data - probably compatible) |
| Teratogenic Risk | Calcium acetate is not teratogenic in animal studies. In pregnancy, calcium supplementation is generally considered safe and may be beneficial for maternal bone health. No increased risk of congenital anomalies has been reported. However, excessive calcium intake could theoretically lead to fetal hypercalcemia or soft tissue calcification, particularly in third trimester. Use within recommended dietary allowances is advised. |
| Fetal Monitoring | Monitor serum calcium and phosphorus levels regularly during pregnancy. Assess for signs of hypercalcemia (polyuria, constipation, hypertension). Fetal ultrasound may be considered if maternal hypercalcemia occurs, but routine monitoring is not required. |
| Fertility Effects | No known adverse effects on fertility. Adequate calcium intake is important for reproductive health. Calcium acetate is used to control hyperphosphatemia in renal disease; underlying condition may affect fertility. |
| Clinical Pearls | Administer with meals to bind dietary phosphate. Monitor serum calcium and phosphate levels; adjust dose to maintain phosphate within target range (0.87–1.45 mmol/L). Avoid use in hypercalcemia. Calcium acetate provides less elemental calcium than calcium carbonate per gram, reducing risk of hypercalcemia. May cause GI side effects; use with caution in patients with renal calculi. |
| Patient Advice | Take this medication exactly as prescribed with each meal or snack to control phosphate levels. · Do not take calcium acetate with other calcium supplements or calcium-containing medications without consulting your doctor. · Report symptoms of high blood calcium such as nausea, vomiting, constipation, confusion, or muscle weakness. · Maintain adequate fluid intake unless fluid restricted by your doctor. · Keep all appointments for blood tests to monitor calcium and phosphate levels. |