[Methemoglobinemia and hemolytic anemia induced by Disulon]

Seven patients ingested (2.5 mg/kg) daily dapsone. Their serum samples were analyzed daily during the first week by spectrophotometry for methaemoglobinemia and weekly blood samples for red blood cells, reticulocytes count and haptoglobin level. The acetylator phenotype of each patient was estimated on the capacity to acetylate isoniazid. Methaemoglobinemia was always observed within the 48 hours after drug intake. The dapsone induced anemia was moderate being maximum between day 25 and 40 after the beginning of treatment. Reticulocytemia appeared in the second week and haptoglobin levels decreased between day 5 and 8 of therapy in 5 patients and at day 15 for the two others. The seven patients are divided in 4 rapid acetylator and 3 slow acetylator. The acetylator phenotype was not correlated with methaemoglobin, haptoglobin levels or RBC counts.