Imuran Overdosage

Symptoms: Unexplained infection, ulceration of the throat, bruising and bleeding are the main signs of overdosage with azathioprine and result from bone marrow depression, which may be maximal after nine to 14 days. These signs are more likely to be manifest following chronic overdosage, rather than after a single acute overdose. There has been a report of a patient who ingested a single overdose of 7.5 g of azathioprine. The immediate toxic effects of this overdose were nausea, vomiting and diarrhoea, followed by mild leukopenia and mild abnormalities in liver function. Recovery was uneventful.
Management: As there is no specific antidote, blood counts should be closely monitored and general supportive measures, together with appropriate blood transfusion, instituted if necessary. Active measures (such as the use of activated charcoal) may not be effective in the event of azathioprine overdose unless the procedure can be undertaken within 60 minutes of ingestion.
Further management should be as clinically indicated or as recommended by the national poisons centre, where available. The value of dialysis in patients who have taken an overdose of azathioprine is not known, though azathioprine is partially dialyzable.
Symptomatic treatment should be administered. Azathioprine is known to be dialyzable and dialysis might be considered in severe cases. Subsequent monitoring, including haematological monitoring, is necessary to allow prompt treatment of any adverse effects which may develop.