A severe case of vasoplegic shock following metformin overdose successfully treated with methylene blue as a last line therapy

Abstract

A 44-year-old man presented to hospital 24 h after an intentional overdose of metformin and gliclazide. He had a critical metabolic acidosis on presentation with a pH of 6.88, and very rapidly deteriorated into distributive shock refractory to large volume fluid resuscitation and massive doses of vasopressors. We introduced a methylene blue infusion as a rescue therapy in an attempt to improve the patient's haemodynamics, which was successful. The patient made a full recovery with no long-term sequelae.

Refractory vasodilatory shock secondary to metformin overdose supported with VA ECMO

“…In this case, methylene blue was given to help reverse the patient’s vasodilatory shock with transient improvement. Methylene blue as a rescue therapy in the setting of metformin toxicity has been previously described in the literature, though infrequently, and has been noted to improve hemodynamics [ [18] , [19] , [20] ]. As an inhibitor of nitric oxide synthase and a competitive inhibitor of nitric oxide, methylene blue reduces the responsiveness of the vasculature to cGMP-mediated vasodilators.…”

Vasopressor-Sparing Action of Methylene Blue in Severe Sepsis and Shock: A Narrative Review

“…In addition to use in septic shock, MB has also been studied in anaphylactic and drug-induced shock or undifferentiated shock [41][42][43][44][45][46]. Medications involved include contrast medium, antidiabetics, antidepressants, and antihypertensives (e.g., amlodipine, atenolol, and valsartan).…”

Clinical Pearls in Medical Toxicology: Updates Ranging From Decontamination to Elimination

“…23 Methylene blue has also been used in the treatment of refractory shock due to metformin, BB, and/or mixed drug overdose. [24][25][26] CCBs cause a dose-related increase in stimulation of nitric oxide release by increasing nitric oxide synthase activity, which in turn increases the generation of cyclic guanosine monophosphate (cGMP) by activation of guanylate cyclase. The accumulation of cGMP produces vasodilatory effects resulting in a drop in systemic vascular resistance.…”

“…In one case of metformin overdose, authors specifically avoided higher doses (5-7 mg/kg) due to well-known incidence of adverse effects at these doses. 24 Possible adverse effects of MB include nausea, vomiting, and blue discoloration of body fluids. Most importantly, hemolytic anemia and serotonin syndrome were not observed in any of the identified cases.…”

“…23 Methylene blue has also been used in the treatment of refractory shock due to metformin, BB, and/or mixed drug overdose. 24 -26…”