Symptoms: Initial symptoms of iron overdosage include nausea, vomiting, diarrhoea, abdominal pain, haematemesis, rectal bleeding, lethargy and circulatory collapse. Hyperglycaemia and metabolic acidosis may also occur. The prolonged release characteristic may delay excessive absorption of iron, and thus allow more time for counter measures to be implemented. However, initial symptoms of overdosage may be absent due to the prolonged release formulation. Therefore, if overdosage is suspected, treatment should be implemented immediately. In severe cases, after a latent phase, relapse may occur after 24-48 hours, manifested by hypotension, coma and hepatocellular necrosis and renal failure.
Treatment: The following steps are recommended to minimise or prevent further absorption of the medication:
Children:
1. Administer an emetic such as syrup of ipecacuanha.
2. Emesis should be followed by gastric lavage with desferrioxamine solution (2g/l). This should then be followed by the instillation of desferrioxamine 5 g in 50-100 ml water, to be retained in the stomach. Inducing diarrhoea in children may be dangerous and should not be undertaken in young children. Keep the patient under constant surveillance to detect possible aspiration of vomitus - maintain suction apparatus and standby emergency oxygen in case of need.
3. Unleached tablets are radio-opaque. Therefore, an abdominal x-ray should be taken to determine the number of tablets retained in the stomach following emesis and gastric lavage.
4. Severe poisoning: in the presence of shock and/or coma with high serum iron levels (serum iron >90 µmol/l) immediate supportive measures plus i.v. infusion of desferrioxamine should be instituted. Desferrioxamine 15 mg/kg body weight should be administered every hour by slow i.v. infusion to a maximum 80 mg/kg/24 hours. Warning: hypotension may occur if the infusion rate is too rapid.
5. Less severe poisoning: i.m. desferrioxamine 1 g 4-6 hourly is recommended.
6. Serum iron levels should be monitored throughout.
Adults:
1. Administer an emetic.
2. Gastric lavage may be necessary to remove drug already released into the stomach. This should be undertaken using desferrioxamine solution (2g/l). Desferrioxamine 5 g in 50-100 ml water should be introduced into the stomach following gastric emptying. Keep the patient under constant surveillance to detect possible aspiration of vomitus; maintain suction apparatus and standby emergency oxygen in case of need.
3. Unleached tablets are radio-opaque. Therefore, an abdominal x-ray of the patient should be taken to determine the number of tablets retained in the stomach following emesis and gastric lavage. The risk/benefit ratio of x-raying pregnant women must be carefully weighed but should be avoided if possible.
4. A drink of mannitol or sorbitol should be given to induce small bowel emptying.
5. Severe poisoning: in the presence of shock and/or coma with high serum iron levels (>142 µmol/l) immediate supportive measures plus i.v. infusion of desferrioxamine should be instituted. The recommended dose of desferrioxamine is 5 mg/kg/h by slow i.v. infusion up to a maximum of 80 mg/kg/24 hours. Warning: hypotension may occur if the infusion rate is too rapid.
6. Less severe poisoning: i.m. desferrioxamine 50 mg/kg up to a maximum dose of 4 g should be given.
7. Serum iron levels should be monitored throughout.