title: Identifying the Cause of the "Saturation Gap": Two Cases of Dapsone-induced Methemoglobinemia.
abstract: Diaphenylsulfone (DDS: Dapsone) is used for Pneumocystis pneumonia (PCP) prophylaxis, and methemoglobinemia has rarely been reported as a side effect of DDS. We herein report two cases of DDS-related methemoglobinemia in an 81-year-old man with organizing pneumonia and an 84-year-old woman with eosinophilic pneumonia under treatment with prednisolone. Both patients initially received trimethoprim/sulfamethoxazole for PCP prophylaxis and were switched to DDS due to side effects and subsequently exhibited a clinically unexplainable decrease in SpO2. Methemoglobinemia was diagnosed based on the findings of arterial blood gas analyses. In both cases, the methemoglobinemia improved after discontinuing DDS.
authors.affiliation: Department of Respiratory Medicine, Kurashiki Central Hospital, Japan.
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Furuta
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ikeo
authors.forename: Takuya
authors.initials: T
authors.lastname: Takaiwa
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ikeda
authors.forename: Akihiro
authors.initials: A
authors.lastname: Nishiyama
authors.forename: Toshihide
authors.initials: T
authors.lastname: Yokoyama
authors.forename: Akihiro
authors.initials: A
authors.lastname: Ito
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Tokioka
authors.forename: Maki
authors.initials: M
authors.lastname: Tanaka
authors.forename: Hiroshige
authors.initials: H
authors.lastname: Yoshioka
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Tachibana
authors.forename: Machiko
authors.initials: M
authors.lastname: Arita
authors.forename: Toru
authors.initials: T
authors.lastname: Hashimoto
authors.forename: Tadashi
authors.initials: T
authors.lastname: Ishida
mesh_terms: D000369:Aged, 80 and over; D000890:Anti-Infective Agents / Q000008:administration & dosage / Q000009:adverse effects*; D019072:Antibiotic Prophylaxis / Q000379:methods; D018549:Cryptogenic Organizing Pneumonia / Q000188:drug therapy*; D003622:Dapsone / Q000008:administration & dosage / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008708:Methemoglobinemia / Q000139:chemically induced* / Q000188:drug therapy; D011020:Pneumonia, Pneumocystis / Q000517:prevention & control*; D016896:Treatment Outcome; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000627:therapeutic use*
chemical_list: D000890:Anti-Infective Agents; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D003622:Dapsone