Acute dapsone poisoning: clinical features and pharmacokinetic studies

A case of acute dapsone poisoning in a 57 year old man is reported. Peak plasma dapsone concentrations of 18.8 mg/l were observed 20 hours after ingestion, and methaemoglobin concentrations fell in parallel with dapsone. Plasma dapsone concentrations declined mono-exponentially with time, and the half-life (29.7 hours) was similar to that described in subjects receiving conventional doses. Moreover, the ratio of monoacetyl-dapsone (MADDS) to dapsone remained constant as plasma concentrations fell. These observations suggest that N-acetylation of dapsone was not saturated even at the toxic concentrations observed.