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 (hydroxocobalamin for injection) 5 g is the only cyanide (CN) antidote that contains hydroxocobalamin1
  • Hydroxocobalamin binds to CN creating nontoxic cyanocobalamin, 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 known or suspected CN poisoning12

Safety Conducive to Empiric Use13,14

  • CYANOKIT 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

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. Consideration should be given to use of alternative therapies, if available. Allergic reactions may include: anaphylaxis, chest tightness, edema, urticaria, pruritus, dyspnea, and rash.  Allergic reactions including angioneurotic edema have also been reported in postmarketing experience.

Substantial increases in blood pressure may occur following CYANOKIT therapy. Elevations in blood pressure (180 mmHg systolic
110 mmHg diastolic) were observed in approximately 18% of healthy subjects receiving hydroxocobalamin 5 g and 28% of subjects receiving 10 g. 

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%) included transient  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

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