When the average person thinks of cyanide poisoning, they might recall its historically dark and purposefully destructive uses – committing crimes, poisoning food, and even self-administered capsules. Old spy movies like You Only Live Twice (or even newer ones like Christopher Nolan’s Tenet) would lead us to believe that every secret agent has a cyanide capsule hidden under a false tooth.
But what they –– and even the medical community –– may not realize, is that these phenomenal accounts aren’t where the real danger lies. We’re often taught that carbon monoxide is a dangerous toxin in fire smoke –– but cyanide is also released when everyday items found in most homes and businesses combust. This includes, but is not limited to, electronics, synthetics, upholstery, pipes, and wood products.
In fact, smoke inhalation from domestic fires is the most common cause of cyanide poisoning in developed countries, with significant levels of cyanide present in up to 35 percent of all fire victims. With an estimated 358,500 home fires occurring every year and exposing people to cyanide.
In colder weather, as people begin to make good use of their fireplaces, space heaters, and light candles, the risk for domestic fires is at its highest. That’s why it’s important for doctors, paramedics, and first responders to recognize the signs and symptoms of cyanide poisoning, and the options to treat it. In this article, we’ll discuss what happens on a cellular level when a patient suffers cyanide toxicity and what steps medical professionals can take if they suspect cyanide poisoning in smoke inhalation patients.
How Cyanide Affects the Body
Cyanide is a broad-spectrum toxin that affects a specific pathway vital to nearly all cells in the body. It binds to an enzyme called cytochrome C oxidase in the cell mitochondria, inhibiting the last step in aerobic cellular respiration.
As a result, oxygen cannot effectively be used. Instead, cells are forced to undergo anaerobic respiration to produce ATP, an energy carrier for tissues and organs across the body. While anaerobic respiration occurs naturally for humans during high-intensity exercise, humans cannot exclusively rely on anaerobic respiration for very long, since toxic byproducts, like lactic acid, build up quickly. Cellular hypoxia and the depletion of ATP occur, leading to metabolic acidosis, and eventually death.
The Three Biggest Indicators of Cyanide Poisoning.
It’s important to remember that diagnosing cyanide poisoning may be difficult, since the presence and extent of cyanide poisoning are often initially unknown. A widely available, rapid, confirmatory cyanide blood test doesn’t exist. With that in mind, treatment decisions should be made based on clinical history, as well as the indicators mentioned below.
Exposure to fire or smoke in an enclosed area
Soot around the mouth, nose, or back of mouth
Altered mental status (e.g., confusion, disorientation)
What Treatment Can Be Administered
There are several approved treatments for cyanide poisoning, though hydroxocobalamin ––CYANOKIT® (hydroxocobalamin for injection) –– is the only product approved by the FDA for the treatment of known or suspected cyanide poisoning. Importantly, CYANOKIT® can be safely administered to patients that are also suffering from carbon monoxide poisoning. CYANOKIT binds to cyanide, creating nontoxic cyanocobalamin (a form of vitamin B12), which then allows the body to use oxygen again.
Another cyanide antidote, Nithiodote (sodium nitrite injection USP and sodium thiosulfate injection USP for intravenous infusion) works by inducing methemoglobin, a state that will reduce the oxygen-carrying capacity of blood. Since carbon monoxide poisoning (which also reduces the oxygen-carrying capacity of blood) often accompanies cyanide poisoning following domestic fires, Nithiodote should be used only with extreme caution and only in very severe cases following smoke inhalation where Cyanokit is unavailable. The FDA has issued a “Black Box Warning”, its most serious warning regarding the use of Nithiodote as nitrites like sodium nitrite(contained in Nithiodote) may cause potentially life-threatening hypotension and its role in forming methemoglobin.
Medical Professionals Should Anticipate Cyanide Toxicity and Be Prepared
Each CYANOKIT® holds one 250-mL glass vial (containing lyophilized hydroxocobalamin for injection, 5g), one sterile transfer spike, one sterile intravenous infusion set, a package insert, and a quick use reference guide. The kit is designed for ease of use and quick setup by professionals in medical facilities, or potentially in the field. Full prescribing information here.
CYANOKIT has been sold in the US by BTG International, Inc. since 15 Dec 2021.
For more information about Cyanokit, ordering information, or to request a demo kit, please visit: https://cyanokit.com/ordering-cyanokit
Jami Johnson, PharmD is a Medical Science Liaison at BTG Specialty Pharmaceuticals
INDICATION
CYANOKIT is indicated for the treatment of known or suspected cyanide poisoning.
Important Safety Information and Indication
WARNINGS AND PRECAUTIONS
Emergency Patient Management
• In conjunction with CYANOKIT, treatment of cyanide poisoning must include immediate attention to airway patency, adequacy of oxygenation and hydration, cardiovascular support, and management of seizures. Consideration should be given to decontamination measures based on the route of exposure.
Risk of Anaphylaxis and Other Hypersensitivity Reactions
• Consider alternative therapies, if available, in patients with known anaphylactic reactions to hydroxocobalamin or cyanocobalamin.
• 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.
Risk of Renal Injury
• Acute renal failure with acute tubular necrosis, renal impairment and urine calcium oxalate crystals have been reported following CYANOKIT therapy. Monitor renal function for 7 days following CYANOKIT therapy.
Risk of Increased Blood Pressure
• Substantial increases in blood pressure may occur following CYANOKIT therapy. Monitor blood pressure during therapy.
Laboratory Tests
• Because of its deep red color, hydroxocobalamin has been found to interfere with colorimetric determination of certain laboratory parameters (e.g., clinical chemistry, hematology, coagulation, and urine parameters). Be aware of this when reporting and interpreting laboratory results.
• While determination of blood cyanide concentration is not required for management of cyanide poisoning and should not delay treatment with CYANOKIT, collecting a pretreatment blood sample may be useful for documenting cyanide poisoning as sampling post-CYANOKIT use may be inaccurate.
Clinical Methods
• 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.
Photosensitivity
• Hydroxocobalamin absorbs visible light in the UV spectrum. It therefore has potential to cause photosensitivity. While it is not known if the skin redness predisposes to photosensitivity, patients should be advised to avoid direct sun while their skin remains discolored.
Pregnancy and Lactation
• Available data from cases reported in the published literature and postmarketing surveillance with CYANOKIT use in pregnant women are insufficient to identify a drug-associated risk for major birth defects, miscarriage, or adverse maternal and fetal outcomes. There are risks to the pregnant woman and fetus associated with untreated cyanide poisoning. In animal studies, hydroxocobalamin administered to pregnant rats and rabbits during the period of organogenesis caused skeletal and soft tissue abnormalities, including alterations in the central nervous system, at exposures similar to human exposures at the therapeutic dose.
• Breastfeeding is not recommended during treatment with CYANOKIT.
ADVERSE REACTIONS
• The most common adverse reactions (>5%) include transient chromaturia, erythema, oxalate crystals in urine, rash, increased blood pressure, nausea, headache and infusion site reactions.
