Hydroxocobalamin

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

Administration

• 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.

References

• Borron SW, Baud FJ, Megarbane B et al. Hydroxocobalamin for severe acute cyanide poisoning by ingestion or inhalation. American Journal of Emergency Medicine 2007; 25:551-518.
• Hall AH, Dart R, Bogdan G. Sodium thiosulfate or hydroxocobalamin for empiric treatment of cyanide poisoning? Annals of Emergency Medicine 2007; 49:806-813.
• Meillier A, Heller C. Acute Cyanide Poisoning: Hydroxocobalamin and Sodium Thiosulfate Treatments with Two Outcomes following One Exposure Event. Case Rep Med. 2015; 2015: 217951.