Iron Overdose Antidote
Deferoxamine is the antidote for acute iron overdose, administered intravenously at 15 mg/kg/hr (maximum rate) for the first 1000 mg, then at a slower rate not exceeding 125 mg/hr, with a total daily dose not exceeding 6000 mg in 24 hours. 1
Route Selection Based on Clinical Presentation
For patients in cardiovascular collapse or shock:
- Use intravenous deferoxamine only 1
- Initial dose: 1000 mg IV at a rate NOT exceeding 15 mg/kg/hr 1
- Subsequent doses: 500 mg over 4 hours for two doses, then 500 mg every 4-12 hours depending on clinical response 1
- Maximum total: 6000 mg in 24 hours 1
For all other patients (hemodynamically stable):
- Use intramuscular deferoxamine as the preferred route 1
- Initial dose: 1000 mg IM 1
- Followed by: 500 mg IM every 4 hours for two doses 1
- Subsequent doses: 500 mg every 4-12 hours based on clinical response 1
- Maximum total: 6000 mg in 24 hours 1
Critical Dosing Considerations
Infusion rate is paramount to prevent hypotension:
- The first 1000 mg must not exceed 15 mg/kg/hr 1
- All subsequent IV doses must be slower, not exceeding 125 mg/hr 1
- High-dose IV deferoxamine causes acute hypotension that is additive with iron-induced hypotension 2
Transition strategy:
- Switch from IV to IM administration as soon as the patient's cardiovascular status permits 1
- This minimizes the risk of deferoxamine-induced hypotension while maintaining chelation 1
Preparation and Administration
For IV use:
- Reconstitute deferoxamine and add to physiologic saline (0.9% or 0.45% sodium chloride), glucose in water, or Ringer's lactate 1
- Administer by slow infusion only, never as IV push 1
For IM use:
Indications for Chelation Therapy
Deferoxamine should be administered when:
- Serum iron concentration exceeds total iron-binding capacity (TIBC) 3
- Acute ingestion >60 mg/kg elemental iron 3
- Signs of severe toxicity: shock, coma, metabolic acidosis, hyperglycemia, leukocytosis 3
- Evidence of systemic iron toxicity regardless of serum iron level 3
Duration of Therapy
Continue deferoxamine until:
- Serum iron returns to normal range (<350 mcg/dL) 3
- Patient is asymptomatic and metabolically stable 3
- Urine color returns to normal (loss of "vin rosé" color indicating ferrioxamine excretion) 3
- Typical duration: 24-48 hours in severe cases 3
Critical Monitoring Parameters
During deferoxamine therapy, monitor:
- Blood pressure continuously (risk of hypotension, especially with IV route) 2, 4
- Serum iron concentrations serially 3
- Urine color (pink/red indicates ferrioxamine complex excretion) 3
- Signs of pulmonary toxicity if therapy exceeds 24 hours 4
- Cardiovascular status (deferoxamine can cause acute cardiovascular collapse at high doses) 4
Important Caveats and Pitfalls
Laboratory interference:
- Deferoxamine reduces iron recovery by up to 50% in serum iron assays at clinically achievable concentrations 5
- Do not rely on serum iron or TIBC measurements obtained during active deferoxamine therapy 5
- Obtain baseline labs before initiating chelation when possible 5
Deferoxamine toxicity risks:
- Pulmonary toxicity with prolonged IV dosing (>24 hours) 4
- Acute respiratory distress syndrome (ARDS) reported with extended therapy 4
- Cardiovascular collapse at high infusion rates 4
- Increased infection risk, particularly with Yersinia and mucormycosis 4
- Ocular and auditory toxicity with chronic use 4
Ineffective interventions:
- Oral deferoxamine does NOT decrease iron absorption and should not be used for gastric decontamination 6
- Equimolar doses of oral deferoxamine do not prevent iron absorption in humans 6
Adjunctive Gastric Decontamination
In addition to deferoxamine:
- Gastric lavage with deferoxamine-containing solution may be considered in severe cases presenting early 3
- Whole-bowel irrigation with polyethylene glycol-electrolyte solution for visible tablets on radiograph 3
- Supportive care including fluid resuscitation, correction of metabolic acidosis, and blood products for GI hemorrhage 3