Chelation therapy

Seek advice from a clinical toxicologist if considering the use of desferrioxamine for chelation therapy in iron poisoning. Desferrioxamine is indicated for patients who have:

• severe systemic toxicity (gastrointestinal bleeding, coma, shock or early metabolic acidosis)
• a peak serum iron concentration more than 90 micromol/L (5 mg/L).

For adults and children, use:

Reduce the desferrioxamine dose by 50% in patients with severe kidney impairment.

The ideal titration of desferrioxamine, and end points for stopping therapy, are unclear. Seek advice from a clinical toxicologist before stopping treatment. Consider stopping desferrioxamine when the serum iron concentration is less than 60 micromol/L (3.35 mg/L), and symptoms and metabolic acidosis are improving; however, systemic symptoms of iron toxicity and metabolic acidosis can persist even after the iron has been chelated.

In general, the duration of desferrioxamine infusion should be limited to 24 hours as prolonged infusion is associated with acute respiratory distress syndrome and respiratory toxicity.

Desferrioxamine can also cause immediate immune-mediated (non-IgE) hypersensitivity reactions including rash, urticaria, flushing, bronchospasm and hypotension. Desferrioxamine-induced hypotension is common, and intravenous fluid loading before treatment is advised.

If hypersensitivity symptoms occur, stop the infusion and treat the reaction as required with intravenous fluids, antihistamines, adrenaline (epinephrine) and inhaled bronchodilators (see also Anaphylaxis). Restart the desferrioxamine at half of the initial rate and gradually increase it back to the initial rate over one hour.

Chelated iron often turns the patient’s urine orange-red.