Methylene blue in the treatment of refractory shock from an amlodipine overdose

Ann Emerg Med. 2011 Dec;58(6):565-7. doi: 10.1016/j.annemergmed.2011.02.025. Epub 2011 May 5.


Amlodipine is a potent vasodilator with a long half-life and delayed onset of action that is particularly concerning after an overdose. Vasodilation occurs through stimulation of nitric oxide release with increased cyclic guanosine monophosphate (cGMP) production. Methylene blue inhibits guanylate cyclase. This enzyme is responsible for the production of cGMP. Methylene blue also has the ability to scavenge nitric oxide, as well as inhibit nitric oxide synthase. We report the use of methylene blue for refractory shock in a patient with amlodipine toxicity.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Amlodipine / poisoning*
  • Cyclic GMP / antagonists & inhibitors*
  • Female
  • Humans
  • Methylene Blue / therapeutic use*
  • Shock / chemically induced*
  • Shock / drug therapy
  • Vasodilator Agents / poisoning*


  • Vasodilator Agents
  • Amlodipine
  • Cyclic GMP
  • Methylene Blue