Mechanism of Action

How Cyanide and CYANOKIT® Work in the Body



Cyanide Prevents Cells From Using Oxygen

  • The ability of oxygen to access the cytochrome oxidase enzyme (present on the mitochondria inside cells) is essential to normal, life-sustaining cellular respiration
  • Cyanide (CN) poisoning may disable the body’s ability to use oxygen so it can be fatal despite the amount of oxygen available to the body1,9
  • Because CN prevents cells from using oxygen, supplemental oxygen alone may be insufficient to treat CN poisoning9

Cyanide Toxicity

  • Moderate to high concentrations of CN can cause severe injury or death within minutes2
  • In massive acute CN poisoning, the mechanism of toxicity may involve other enzyme systems1
  • CN poisoning may also cause central nervous system side effects including intellectual impairment, Parkinson-type effects, and personality changes10

Hydroxocobalamin Treats Cyanide Poisoning

  • CYANOKIT® 5 g (hydroxocobalamin for injection) is the only cyanide (CN) antidote that contains hydroxocobalamin1
  • Hydroxocobalamin binds to CN, allowing the body to use oxygen again1,9


  • CYANOKIT® has been used to treat multiple sources of CN poisoning including smoke inhalation and ingestion1,5,11,12
  • Hydroxocobalamin has been used in France since 1996 and in the United States since 2007 to treat suspected or known CN poisoning12

Safety Conducive to Empiric Use13,14

  • Studies have shown CYANOKIT® to be generally well-tolerated even in the absence of CN poisoning1,4,11,13

CYANOKIT® (hydroxocobalamin for injection) 5 g for intravenous infusion is indicated for the treatment of known or suspected cyanide poisoning. If clinical suspicion of cyanide poisoning is high, CYANOKIT® should be administered without delay.

Important Safety Information
Cyanide poisoning may result from inhalation, ingestion, or dermal exposure. Prior to administration of CYANOKIT®, smoke-inhalation victims should be assessed for: exposure to fire or smoke in an enclosed area; presence of soot around the mouth, nose, or oropharynx, and altered mental status. In addition to CYANOKIT®, treatment of cyanide poisoning must include immediate attention to airway patency, adequacy of oxygenation and hydration, cardiovascular support, and management of any seizure activity.

Use caution in the management of patients with known anaphylactic reactions to hydroxocobalamin or cyanocobalamin. Allergic reactions may include: anaphylaxis, chest tightness, edema, urticaria, pruritus, dyspnea, rash, and angioneurotic edema. Substantial increases in blood pressure may occur following CYANOKIT® therapy. Usage may interfere with some clinical laboratory evaluations. Also, because of its deep red color, hydroxocobalamin may cause hemodialysis machines to shut down due to an erroneous detection of a "blood leak." This should be considered before hemodialysis is initiated in patients treated with hydroxocobalamin. Due to potential photosensitivity, patients should avoid direct sun until erythema resolves.

CYANOKIT® is Pregnancy Category C and should be used during pregnancy only if the potential benefit justifies the potential risk. Safety and effectiveness of CYANOKIT® have not been established in pediatric patients. The most common adverse reactions (>5%) are transient and include chromaturia, erythema, rash (predominantly acneiform), increased blood pressure, nausea, headache, decreased lymphocyte percentage, and injection site reactions.

Please see single 5-g vial full Prescribing Information. Please see two 2.5-g vial full Prescribing Information.

This Web site is intended only for First Responders and Healthcare Professionals and is subject to all applicable US laws. The product information provided in this site is intended only for residents of the United States. The products discussed herein may have different product labeling in different countries.