Methylene blue as treatment for vasoplegic shock in severe metformin overdose: A case report

INTRODUCTION: Severe metformin overdose can result in life-threatening conditions such as metabolic acidosis with hyperlactatemia and vasoplegic shock. Current treatment guidelines recommend hemodialysis and supportive care. However, this case report presents the use of methylene blue as an additional treatment for severe metformin overdose-induced vasoplegic shock, which is not commonly described in the literature or guidelines. CASE REPORT: A 55-year-old woman presented to the emergency department after ingesting 82.5 g of metformin, resulting in severe metabolic acidosis with hyperlactatemia and refractory vasoplegic shock. Despite continuous hemodialysis and high levels of noradrenalin and vasopressin, the shock persisted. Methylene blue was administered, leading to an immediate and persistent reduction in the noradrenalin dose and rapid shock resolution. DISCUSSION: This case illustrates the potential use of methylene blue in the treatment of severe metformin overdose. The mechanism for metformin-induced vasoplegia is likely mediated by nitric oxide (NO). Methylene blue has been used to treat NO-mediated vasoplegia in other conditions, such as sepsis and poisoning with beta-blockers and calcium channel blockers, but it is rarely described in metformin toxicity. Methylene blue has a rapid onset of action, with only a few mild side effects. This case report emphasizes the need for clinicians to consider methylene blue as a potential treatment option in cases of refractory vasoplegic shock due to severe metformin overdose.