FERRIC CITRATE
Clinical safety rating: caution
Comprehensive clinical and safety monograph for FERRIC CITRATE (FERRIC CITRATE).
Ferric citrate dissociates to provide ferric iron, which binds dietary phosphate in the gastrointestinal tract, forming insoluble ferric phosphate that is excreted in feces, thereby reducing serum phosphate levels. It also provides iron for erythropoiesis.
| Metabolism | Not metabolized; iron is absorbed and incorporated into hemoglobin or stored as ferritin; phosphate-bound iron is excreted unchanged in feces. |
| Excretion | Primarily fecal as unabsorbed iron (≥90%); minimal renal excretion (<1%) of absorbed iron. |
| Half-life | Approximately 6 hours for absorbed iron; clinical effect on serum phosphate occurs within 1–2 weeks. |
| Protein binding | Absorbed iron is extensively bound to transferrin (≈99.9%); unbound iron is minimal. |
| Volume of Distribution | 2–5 L/kg for absorbed iron, reflecting distribution into reticuloendothelial system and erythroid precursors. |
| Bioavailability | Oral: Very low (1–5%) due to limited absorption and active efflux; absorption increases with iron deficiency. |
| Onset of Action | Oral: Reduction in serum phosphate observed within 1 week; maximal effect by 4–6 weeks. |
| Duration of Action | Duration of phosphate-binding effect is approximately 24 hours with thrice-daily dosing; clinical effect persists as long as therapy continues. |
| Molecular Weight | 244.88 |
1-2 tablets (210-420 mg elemental iron) orally three times daily with meals.
| Dosage form | TABLET |
| Renal impairment | No dose adjustment required for chronic kidney disease; contraindicated if GFR <30 mL/min/1.73 m² due to risk of iron overload. |
| Liver impairment | No dose adjustment recommended for hepatic impairment; use with caution in severe Child-Pugh C. |
| Pediatric use | Not recommended for children <6 years; for children ≥6 years: 1 tablet (210 mg elemental iron) orally three times daily with meals. |
| Geriatric use | No specific dose adjustment; monitor for gastrointestinal adverse effects. |
| 1st trimester | Minimal data; iron replacement generally considered safe. Use only if clearly needed. |
| 2nd trimester | Safe for treatment of iron deficiency; monitor ferritin levels. |
| 3rd trimester | Safe; used for anemia and hyperphosphatemia in CKD; monitor iron parameters. |
Clinical note
Comprehensive clinical and safety monograph for FERRIC CITRATE (FERRIC CITRATE).
| Placental transfer | Limited data in humans. Based on molecular weight and low oral bioavailability, placental transfer is likely minimal. |
| Breastfeeding | Ferric citrate is a large complex with minimal oral absorption, making it unlikely to pass into breast milk at significant levels. It is generally considered compatible with breastfeeding, but caution is advised when used for hyperphosphatemia due to theoretical risk of iron overload in the infant. Consult infant's healthcare provider. |
■ FDA Black Box Warning
None
| Serious Effects |
Iron overload (e.g., hemochromatosis)Hypersensitivity to ferric citrate or any component
| Precautions | Risk of iron overload, especially in patients with serum ferritin >500 ng/mL or transferrin saturation >50%, May increase serum calcium due to reduced phosphate binding of calcium, Gastrointestinal adverse reactions including diarrhea, constipation, nausea, and vomiting, Potential for aluminum absorption if taken with aluminum-containing antacids |
| Food/Dietary | Administer with meals to maximize phosphate binding. Avoid high-phosphate foods (dairy, nuts, cola) but this is disease-related, not a drug interaction. No specific food restrictions other than phosphate-controlled diet. Do not take with aluminum-containing antacids (reduce efficacy). |
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| Lactation Rating | L2 (Probably Compatible) |
| Teratogenic Risk | No human data; animal studies not available. Iron is essential for fetal development; however, excessive iron may be harmful. Risk cannot be excluded; use only if clearly needed. |
| Fetal Monitoring | Monitor maternal hemoglobin, serum ferritin, and iron indices (total iron-binding capacity, transferrin saturation) periodically. Assess for signs of iron overload or deficiency. No specific fetal monitoring required. |
| Fertility Effects | No known adverse effects on fertility. Iron deficiency may impair fertility; supplementation may improve outcomes. No data on direct effects of ferric citrate. |
| Clinical Pearls | Ferric citrate is a phosphate binder used in CKD patients on dialysis. It also increases serum iron and ferritin, potentially reducing ESA and IV iron needs. Monitor for iron overload (transferrin saturation >50%, ferritin >800 ng/mL). Can cause GI discoloration (dark stools) and hypophosphatemia if overused. Avoid in non-dialysis CKD patients due to risk of iron accumulation. |
| Patient Advice | Take with meals to bind dietary phosphate. · Expect dark or black stools (harmless). · Do not take with other iron supplements unless directed. · Report persistent GI upset, constipation, or diarrhea. · Keep consistent dosing schedule; do not skip doses. · Store at room temperature, away from moisture. |