Case Series: Phenazopyridine-Induced Methemoglobinemia in the Context of Intoxication

Abstract

Abstract: Phenazopyridine, a medication used for decades to treat urinary tract issues, can rarely cause methemoglobinemia, a potentially serious condition. This article presents two cases of overdose-related intoxication, both with severe manifestations, including refractory cyanosis to oxygen therapy, which required treatment with methylene blue. Both patients exhibited renal impairment, with one requiring hemodialysis. Methemoglobinemia occurs due to the oxidation of hemoglobin, and while clinical suspicion is an important factor, laboratory evaluation is essential for diagnosis and monitoring. The primary treatment is methylene blue, effective in reducing methemoglobin levels above 20-30%, but careful monitoring of effects and contraindications, such as G6PD deficiency, is necessary. These cases highlight the importance of thorough clinical assessment and early recognition of this condition in cases of unexplained cyanosis, given the risk of fatal outcomes.

Key words: Acquired methemoglobinemia; Community emergency medicine; Metabolic; Methemoglobinemia; Methylene Blue; Phenazopyridine; Poisoning; Respiratory support; Toxicology