Dapsone-induced Methemoglobinemia Case Report

Abstract

Methemoglobinemia is a rare disorder associated with an elevated methemoglobin level that occurs when hemoglobin is in the oxidized ferric ion form rather than reduced ferrous form. In patients with methemoglobinemia, the hemoglobin with oxidized ferric form cannot release oxygen to the tissues which leads to hypoxemia. Methemoglobinemia can be acquired or inherited. The acquired methemoglobinemia happens in patients after they take certain oxidizing drugs. This disorder is mostly treated with 2 mg/kg methylene. This disorder is mostly treated with 2 mg/kg methylene blue. However, administrating ascorbic acid as an antioxidant may also helpful, especially if a patient has taken two doses of methylene blue or if the use of methylene blue is contraindicated. Methemoglobinemia may not cure or may rebound after response to treatment, especially with long half-life drugs such as dapsone. As it states in the leaflet for methylene blue, if methemoglobinemia does not resolve after two doses, one should initiate another alternative. Ascorbic acid is a good alternative because it is an antioxidant to keep tissue from harm of free radicals and also has a role in reducing methemoglobin via co-factor nicotinamide adenine dinucleotide phosphate reeducates needed for glutathione metabolism. We discuss a case of methemoglobinemia treated successfully with oral ascorbic acid after using two doses of methylene blue. Oral ascorbic acid could be beneficial, especially when the patient was taken two doses of methylene blue.