The mystery of 'saturation gap': a case of dapsone-induced methaemoglobinemia in a pregnant mother with leprosy.

Abstract

Limited data regarding methemoglobinemia in pregnancy, particularly secondary to dapsone is available up to date. We report a case of dapsone-induced methemoglobinemia in a pregnant mother with multibacillary leprosy who presented with fever, productive cough and cyanosis of 2 days duration 2 weeks after multidrug therapy was commenced. On examination, she had central cyanosis with low oxygen saturation (SpO2 = 84-88%). Arterial blood gas analysis showed PO2 of 111 mmHg and SO2 of 98 mmHg. Patient was administered 100% oxygen inhalation, but there was no improvement in cyanosis. Vitamin C (1000 mg/day) was prescribed. Dapsone was replaced by ofloxacin 200 mg twice daily. There was a gradual increase in SpO2 level. She delivered a healthy baby. In conclusion, clinicians should be aware of the side effects of dapsone and know how to promptly manage any undesirable events. Ofloxacin is a safe and feasible alternative in replacement of dapsone in pregnancy.

• Authors: Andy Sing Ong Tang, Siaw Tze Yeo, Yeon Chiat Teh, Wee Meng Kho, Lee Ping Chew, Pubalan Muniandy
• Journal: Oxford medical case reports (Oxf Med Case Reports) Vol. 2019 Issue 1 Pg. omy111 (Jan 2019) ISSN: 2053-8855 [Print] England
• PMID: 30697428 (Publication Type: Case Reports)