Hydroxocobalamin is a vitamin B12 (cyanocobalamin) precursor. In high doses, it is an effective chelator of cyanide. It is also the preferred antidote to cyanide poisoning due to its low side effect profile, thus if given to a patient without cyanide poisoning there is low risk of an adverse outcome


  • Reconstitute 1 ampoule (2.5g) with 100ml of 0.9% saline. Administer IV over 15 minutes.
  • Repeat the process with the second ampoule.
  • This should be sufficient to bind 100 mg of cyanide, if more have been ingested then further dosing will be required.
  • If no improvement within 15 minutes then repeat administration or administer sodium thiosulfate (not in the same infusion)
  • Therapeutic end points: Improved conscious state, haemodynamic stability and improvement in the metabolic acidosis
  • In Cardiac Arrest – administer 5g IV push.


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Toxicology Library


Dr Neil Long BMBS FACEM FRCEM FRCPC. Emergency Physician at Kelowna hospital, British Columbia. Loves the misery of alpine climbing and working in austere environments (namely tertiary trauma centres). Supporter of FOAMed, lifelong education and trying to find that elusive peak performance.

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