Methylene blue

Methylene blue

• Methylene blue is a medication that has several important indications. The two main indications are:
  1. Methemoglobinemia: This is a condition in which hemoglobin decreases its ability to carry oxygen, and methylene blue is used in the management and treatment of this condition.
  2. Refractory distributive shock: Methylene blue is used to increase systemic vascular resistance when the use of epinephrine is refractory in vasoplegic syndrome, a type of distributive shock that occurs during coronary procedures.
  

• Methylene blue is also used during either a lumpectomy/mastectomy with sentinel lymph node biopsy, as it is applied as a dye to map out which lymph nodes, if any, have any signs of malignancy.
  
• Methylene blue is contraindicated in patients who have demonstrated hypersensitivities or anaphylaxis after past administration and for those with glucose-6-phosphate dehydrogenase deficiency due to susceptibility to experiencing hemolytic anemia. Those experiencing hemolytic anemia under this situation will have jaundice and other symptoms.

• Methylene blue is a safe drug when used in therapeutic doses, but it can cause toxicity in high doses. The features of toxicity include cardiac arrhythmias, coronary vasoconstriction, decreased cardiac output, renal blood flow and mesenteric blood flow, increased pulmonary vascular pressure and pulmonary vascular resistance, and gas exchange deterioration.
• It also turns urine greenish-blue and causes bluish discoloration of skin and mucosa, which is self-limiting.

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Two important indications of methylene blue:
【1】Methemoglobinemia
【2】Refractory distributive shock

#Toxicology

References:

Methylene Blue for Distributive Shock: a Potential New Use of An Old Antidote. Jang DH, Nelson LS, Hoffman RS. J Med Toxicol. 2013;9(3):242-9.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3770994/

Methylene blue used in treatment of refractory shock resulting from drug poisoning. Fischer J. Taori G. et al. Clin Toxicol 2014 Jan;52(1) 63-65.

Calcium channel antagonist and beta blocker overdoses: antidotes and adjunct therapies. Graudins A, Lee HM, Druda D. Br J Clin Pharmacol. 2016 Mar 81(3):453-61.

A Review of Methylene Blue Treatment for Cardiovascular Collapse. Lo A, Jean CY, et al. Journal of Emerg Med. May 2014. Vol 46 (6): 670-679.

A Systematic Analysis of methylene Blue for Drug-Induced Shock. Warrick BJ, Tataru AP, Smolinske S. Clin Toxicol 2016 Aug;54(7):547-55.