Acute dapsone intoxication: a case with prolonged symptoms.

A 45-year-old man ate about 10 gm of dapsone (DDS). After initial vomiting marked methemoglobinemia with cyanosis, headache, and confusion developed. Methemoglobinemia subsided 7 days after ingestion when the concentrations of DDS and monoacetyldapsone (MADDS) were at the therapeutic level. Signs of hemolysis appeared on the third day after DDS ingestion, the hemolysis being maximal more than one week after ingestion. The initial disappearance of DDS and MADDS was slow, the apparent half-lives being 88 and 67 hr, respectively. Peroral activated charcoal seemed to shorten the half-lives of DDS and MADDS markedly. This result supports the concept of the enterohepatic cycle of dapsone and recommends the use of activated charcoal for several days in acute poisonings caused by DDS.