Apri 23, 2007: What is the CYANOKIT (hydroxocobalamin) antidote?


Cyanokit was FDA approved about a month ago.  Cyanokit contains hydroxocobolamin, the hydroxylated active form of vitamin B12 ,an antidote indicated for the treatment of cyanide poisoning.

Inhalation, ingestion or dermal exposure to cyanide-containing compounds may cause cyanide poisoning.  Cyanide binds rapidly with cytochrome a3 in the mitochondria.  Inhibition of this cytochrome prevents the cell from using oxygen and forces anaerobic metabolism, resulting in lactate production, cellular hypoxia, and metabolic acidosis.   Signs and symptoms of acute cyanide poisoning may develop within minutes.

Administration of cyanokit (hydoxocobolamin) to cyanide-poisoned patients results in formation of cyanocobalamin which is excreted in the urine.  Each hydroxocobalamin molecule binds one cyanide ion.  Cyanokit is administered intravenously over 15 minutes.  The drug appears to be fairly safe.  Side effects have included allergic reactions, rash, red urine, increased blood pressure, and injection site reactions. The previous Lily Cyanide kit used agents that induced methemoglobinemia, so there was the potential to increase the hypoxia.   

The real use for this kit is going to be in the field and in the ED.  One of the main sources of cyanide poisoning is burning plastics, a material that burns in most house fires.  The problem is there is no quick test to determine which burn victims with smoke inhalation also have cyanide poisoning. 

Dr. Jeff Guy, Chief of the Vanderbilt Burn Unit, recommends that hydroxocobalamin (Cyanokit) be administered in burn patients with the following:  previously entrapped; CO greater than 10% in nonsmokers; burns to the face; burns to the chest; change in character of voice, or difficulty with secretions. 

Clinical signs and symptoms of Cyanide toxicity will be discussed in the next Question of the Week.

I am interested in any questions you would like answered in the Question of the Week.  Please email me with any suggestion at donna.seger@vanderbilt.edu.


Donna Seger, MD

Medical Director

Tennessee Poison Center

Website: www.tnpoisoncenter.org