FERRISELTZ
Clinical safety rating: caution
Comprehensive clinical and safety monograph for FERRISELTZ (FERRISELTZ).
Ferric iron (Fe3+) from ferric citrate reduces phosphate absorption by forming insoluble ferric phosphate complexes in the gastrointestinal tract, reducing serum phosphate levels. Iron is absorbed and incorporated into hemoglobin.
| Metabolism | Ferric citrate dissociates to ferric ions; iron is utilized for erythropoiesis. Non-absorbed iron is excreted in feces. |
| Excretion | Ferric citrate is primarily eliminated via feces as unabsorbed drug (approximately 70-80%). A small fraction is absorbed and excreted renally (less than 1% of ingested dose). |
| Half-life | Not applicable for iron absorption; serum iron levels peak at 1-2 hours post-dose and decline with a half-life of approximately 6 hours, reflecting gastrointestinal absorption and distribution. |
| Protein binding | Ferric ion binds to transferrin (>99%) after absorption; unabsorbed iron is not protein-bound. |
| Volume of Distribution | Not applicable; iron is distributed to body iron stores (Vd approx 0.1 L/kg for absorbed iron, reflecting plasma and transferrin compartment). |
| Bioavailability | Oral: Approximately 0.1-1% absorbed; fractional absorption depends on iron stores, with higher absorption in deficiency. |
| Onset of Action | Oral: Reduction in serum phosphate begins within 1 week of dosing; maximal effect seen at 2-4 weeks. |
| Duration of Action | Duration of phosphate-binding effect persists for 4-6 hours after a single dose; requires multiple daily dosing for sustained control. |
325-650 mg orally once daily; ferrous sulfate 325 mg (equivalent to 65 mg elemental iron).
| Dosage form | FOR SOLUTION |
| Renal impairment | No specific GFR-based dose adjustment; use with caution in severe renal impairment (eGFR <30 mL/min) due to risk of iron overload. |
| Liver impairment | No specific Child-Pugh based adjustment; monitor iron levels in severe hepatic impairment. |
| Pediatric use | Prophylaxis: 1-2 mg/kg/day elemental iron orally; Treatment: 3-6 mg/kg/day elemental iron orally in divided doses. Maximum 15 mg/day elemental iron. |
| Geriatric use | Initial 325 mg ferrous sulfate (65 mg elemental iron) orally once daily; increase to twice daily if tolerated. Monitor for constipation and iron overload. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for FERRISELTZ (FERRISELTZ).
| Breastfeeding | Iron is normally present in breast milk. Ferric citrate use is compatible with breastfeeding. M/P ratio not established for ferric citrate specifically; milk iron levels are regulated and supplementation increases milk iron minimally. No adverse effects on infant reported. |
| Teratogenic Risk | FERRISELTZ (ferric citrate) is an iron-containing product. Iron is essential for fetal development, but excessive iron may be harmful. No teratogenic effects are expected at recommended doses. First trimester: No evidence of fetal harm from iron supplements. Second/Third trimester: Iron needs increase; supplementation is safe and indicated for iron deficiency anemia. Overdose may cause iron toxicity. |
■ FDA Black Box Warning
None.
| Serious Effects |
["Hemochromatosis","Other iron overload syndromes","Hypersensitivity to ferric citrate or any component"]
| Precautions | ["Risk of iron overload; monitor serum ferritin and transferrin saturation","Gastrointestinal adverse effects (discolored stools, nausea, constipation)","May increase vitamin D analog absorption; monitor serum calcium and phosphate levels","Not for patients with iron overload syndromes"] |
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| Fetal Monitoring | Monitor hemoglobin, hematocrit, serum ferritin, and iron studies periodically. Assess iron status before and during therapy. For maternal toxicity: monitor for signs of iron overload or gastrointestinal intolerance. Fetal monitoring: none specific beyond routine prenatal care. |
| Fertility Effects | No known adverse effects on fertility. Iron supplementation may improve fertility in women with iron deficiency anemia by correcting anemia. |