PHOSLO
Clinical safety rating: caution
Comprehensive clinical and safety monograph for PHOSLO (PHOSLO).
Calcium acetate binds phosphate in the gastrointestinal tract, forming insoluble calcium phosphate that is excreted in feces, thereby reducing serum phosphate levels.
| Metabolism | Calcium acetate is not metabolized; it dissociates in the gastrointestinal tract to release calcium, which may be absorbed. Absorbed calcium is handled by normal calcium metabolic pathways. |
| Excretion | Primarily fecal as unabsorbed drug; minimal renal elimination (<0.5%) |
| Half-life | Not applicable; minimal systemic absorption, local gastrointestinal action |
| Protein binding | Not significantly protein bound; acts locally in gut lumen |
| Volume of Distribution | Not applicable; minimal systemic absorption |
| Bioavailability | Less than 0.5% (systemic absorption negligible) |
| Onset of Action | 1-2 hours (intestinal phosphate binding) |
| Duration of Action | 6-8 hours (binds dietary phosphate during intestinal transit) |
| Molecular Weight | 158.17 |
667 mg (two 667-mg tablets or one 667-mg capsule) orally three times daily with meals, titrated to maintain serum phosphate between 3.5-5.5 mg/dL; maximum 4000 mg/day.
| Dosage form | TABLET |
| Renal impairment | Contraindicated in hyperphosphatemia with CrCl <25 mL/min due to risk of aluminum accumulation; use alternative phosphate binders. For CrCl 25-50 mL/min, initiate at 667 mg with meals and monitor serum aluminum and phosphate levels closely. |
| Liver impairment | No specific adjustment for hepatic impairment; caution in severe hepatic disease due to potential for铝 accumulation (noted in literature but not guideline-defined). Use standard dosing with monitoring. |
| Pediatric use | For children ≥2 years: 667 mg (or 10-20 mg/kg) orally three times daily with meals; titrate to maintain serum phosphate in age-appropriate normal range (4.0-6.0 mg/dL for children). Maximum 2000 mg/day. |
| Geriatric use | No specific dose adjustment; initiate at low end of dosing range (667 mg with meals) due to potential for decreased renal function. Monitor serum calcium, phosphate, and aluminum levels routinely. |
| 1st trimester | No known teratogenic effects; calcium acetate is not absorbed systemically in significant amounts. However, ensure adequate phosphate control without inducing hypercalcemia. |
| 2nd trimester | Minimal systemic absorption; use with caution to avoid maternal hypercalcemia which may affect fetal calcium metabolism. |
| 3rd trimester | Avoid hypercalcemia as it may suppress fetal parathyroid hormone and cause neonatal hypocalcemia. |
Clinical note
Comprehensive clinical and safety monograph for PHOSLO (PHOSLO).
| Placental transfer | Minimal placental transfer due to low systemic absorption; calcium from the salt may cross but is not significant given endogenous calcium regulation. |
| Breastfeeding | Calcium acetate is minimally absorbed systemically and unlikely to enter breast milk in significant amounts. However, monitor maternal serum calcium as hypercalcemia could theoretically affect the infant. Considered compatible with breastfeeding with caution. |
■ FDA Black Box Warning
None.
| Serious Effects |
HypercalcemiaHypersensitivity to calcium acetate or any component of the formulation
| Precautions | Hypercalcemia: Monitor serum calcium levels; risk increases with concurrent vitamin D or calcium supplements., Digitalis toxicity: Hypercalcemia may precipitate arrhythmias in patients on digitalis., Gastrointestinal effects: Nausea, vomiting, constipation, or bowel obstruction., Soft tissue calcification: Prolonged elevated calcium-phosphate product may lead to vascular or soft tissue calcification. |
| Food/Dietary | Take with meals to bind dietary phosphate. Avoid high-phosphate foods such as dairy, nuts, beans, cola, and processed meats. Calcium-containing foods may increase calcium load; monitor intake if hypercalcemia risk. |
Loading safety data…
| Lactation Rating | L2 (Safer) |
| Teratogenic Risk | Pregnancy Category C. No adequate studies in pregnant women. Calcium acetate is not systemically absorbed; thus, fetal exposure is minimal. However, maternal hypercalcemia could affect fetal parathyroid development. First trimester: theoretical risk of hypercalcemia-induced fetal anomalies; second and third trimesters: risk of fetal hypoparathyroidism if maternal calcium levels are elevated. |
| Fetal Monitoring | Monitor serum calcium, phosphorus, and parathyroid hormone levels regularly; avoid hypercalcemia. Assess maternal renal function. Fetal monitoring: consider ultrasound for fetal parathyroid gland development if maternal hypercalcemia occurs. |
| Fertility Effects | No known impact on fertility. Calcium acetate does not affect reproductive hormones or function. |
| Clinical Pearls | Administer with meals to maximize binding to dietary phosphate. Do not use in patients with hypercalcemia or hypoparathyroidism. Monitor serum calcium and phosphate levels regularly. Avoid concurrent use with oral tetracyclines or fluoroquinolones due to chelation; separate by at least 2 hours. |
| Patient Advice | Take this medication with every meal or snack to bind phosphate in food. · Swallow capsules whole; do not crush or chew. · Maintain a low-phosphate diet as directed by your healthcare provider. · Do not take with other oral medications; wait at least 2 hours before or after taking other drugs. · Report symptoms of high calcium like nausea, vomiting, confusion, or muscle weakness. |