Clofazimine-induced methemoglobinemia: A rare incidence

Clofazimine is commonly used for the treatment of leprosy and chronic use of it can lead to methemoglobinemia, which is a rare but major concern. Iron of hemoglobin remains in the form of ferric (Fe3+) in methemoglobinemia as compared with ferrous form (Fe2+) in normal situation. This transformation prevents oxygen carriage and results in higher level of MetHb in blood which could be dangerous to life. In normal patients the level of MetHb is <1%. We report a case where acute ingestion of many tablets of clofazimine resulted in methemoglobinemia. Cyanosis was not apparent in this case leading to delayed diagnosis, and despite >30% MetHb levels, the clinical presentation was not very suggestive. Because of the nonavailability of intravenous methylene blue and parenteral ascorbic acid, tablet ascorbic acid was used for the management. Gradual decrease of MetHb levels was observed, with amelioration of symptoms and improvement in patient's condition. Review of the literature failed to reveal publication of acute methemoglobinemia with such presentation in the past. Awareness about possibility of methemoglobinemia and its possible contributors will help primary care physician and emergency physician suspect this condition early in patients presenting with history of unknown drug overdose and work in proper direction.