Abstract
A 15-year-old girl presented after intentional ingestion of dapsone (7.2 g) and small quantities of azathioprine, methotrexate and prednisolone. The resulting methaemoglobinaemia and lactic acidosis persisted despite treatment with methylene blue, multiple-dose activated charcoal and ascorbic acid. Continuous veno-venous haemofiltration for 75 hours was used to treat the dapsone overdose. The patient's serum dapsone concentrations were measured during and after continuous veno-venous haemofiltration. The rate of elimination of dapsone was over three times higher during, compared to after, continuous veno-venous haemofiltration. Continuous renal replacement therapy successfully reduced toxic dapsone concentrations in this patient with a good outcome.