A study of iron complexation in a swine model.

The treatment of iron poisoning consists of supportive care and efforts to remove or retard the absorption of iron from the gastrointestinal tract. A standard but rarely challenged treatment is to render the unabsorbed iron less soluble by complexing it with bicarbonate or phosphate solution. Another therapy is the use of oral deferoxamine. Bicarbonate and phosphate therapy are known to be associated with adverse outcomes if used inappropriately. Is their use justified? To closely simulate a potentially toxic iron overdose in a 24-month-old child, a swine model was used. Twenty fasted castrated male pigs weighing an average of 14.6 kg (+/- 3.0 kg) were orally dosed with 300 mg/kg FeSO4 (60 mg Fe/kg) and randomly placed into 1 of 4 treatment groups receiving 50 ml of distilled water (control), 5% sodium bicarbonate, 5% sodium dihydrogen phosphate, or deferoxamine (10 g). Sequential serum iron levels were obtained at 0, 1, 2, 4, and 6 hr. There were no significant differences in the absorption of iron, as reflected by serum iron concentrations, in the bicarbonate and phosphate groups when compared to the control group (p greater than 0.05). Deferoxamine therapy reduced iron serum concentrations, ie iron absorption, significantly (p less than 0.05) when compared to the control, bicarbonate and phosphate groups. This study provides evidence that efforts to form digestive tract complexation of iron with bicarbonate or phosphate are of no value.