Iron Poisoning - Antidote & Management

The Antidote: Deferoxamine

Deferoxamine (desferrioxamine) is the chelating agent of choice for severe iron poisoning. It is isolated from the bacterium Streptomyces pilosus and works by binding free iron that is not already bound to organic molecules.

Mechanism of Action

Binds free iron in plasma and inside cells and mitochondria
Competes for loosely bound iron in iron-carrying proteins (hemosiderin and ferritin)
Does not compete for biologically chelated iron in cytochromes or hemoproteins - so it does not disrupt normal iron-dependent enzymes
Forms the complex ferroxamine, which is renally excreted, often turning the urine a characteristic orange-red ("vin rose") color

Why IV, Not Oral

Deferoxamine is poorly absorbed orally and may even increase iron absorption when given by mouth. It must be administered intravenously (or IM in less severe cases).

Dosing & Indications

Deferoxamine is indicated when:

Peak serum iron concentration is > 500 μg/dL, OR
Patient has severe signs and symptoms regardless of iron level (shock, metabolic acidosis, persistent vomiting, altered mental status)

Serum iron levels at 3 and 6 hours after ingestion are used to determine toxicity.

Rosen's Emergency Medicine notes: 9 mg of elemental iron is chelated per 100 mg of deferoxamine - meaning only a small fraction of total ingested iron is chelated, but this is clinically sufficient to reduce free-iron toxicity.

Stages of Iron Toxicity (What You're Treating)

Stage	Time	Features
I	0-6 hr	GI: vomiting, diarrhea, GI hemorrhage
II	6-24 hr	Apparent recovery
III	12-48 hr	Metabolic acidosis, shock, hepatotoxicity
IV	2-5 days	Hepatic failure
V	2-6 weeks	GI scarring, pyloric stenosis

GI Decontamination (Before or Alongside Chelation)

Whole-bowel irrigation with polyethylene glycol (250-500 mL/h in children, 2 L/h in adults) is the decontamination method of choice - especially when radiopaque tablets are visible on X-ray
Do NOT use: activated charcoal (does not adsorb iron), ipecac, oral sodium bicarbonate, or phosphosoda
Orogastric lavage is rarely helpful unless performed very shortly after a large ingestion
Endoscopy or laparoscopic gastrotomy may be needed to remove an iron bezoar in severe cases

Adverse Effects of Deferoxamine

Hypotension - with rapid IV infusion (infuse slowly)
Flushing, abdominal discomfort, rash
ARDS - with infusions lasting > 24 hours (so treatment is typically limited)
Neurotoxicity and increased susceptibility to Yersinia enterocolitica infections with long-term use
In renal failure: hemodialysis may be needed to remove the ferroxamine complex

Other Iron Chelators (for Chronic Overload, Not Acute Poisoning)

Drug	Route	Use
Deferasirox	Oral	Transfusional iron overload (thalassemia, MDS); FDA-approved 2005
Deferiprone	Oral	Second-line for thalassemia; risk of agranulocytosis (~1%); FDA-approved 2011

These oral chelators are used for chronic iron overload (e.g., transfusion-dependent hemoglobinopathies), not acute poisoning.

Key Point Summary

Item	Detail
Antidote	Deferoxamine
Route	IV (preferred), IM
Mechanism	Chelates free iron → ferroxamine (renally excreted)
Indication threshold	Serum Fe > 500 μg/dL or severe symptoms
Urine color change	Orange-red ("vin rose") confirms chelation is working
Duration limit	Avoid > 24 hr continuous infusion (ARDS risk)
Do NOT give	Oral deferoxamine, activated charcoal

Sources: Rosen's Emergency Medicine, p. 2980 | Tintinalli's Emergency Medicine, p. 2863-2914 | Katzung's Basic & Clinical Pharmacology 16e, p. 2818 | Goodman & Gilman's Pharmacological Basis of Therapeutics

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