From the Guidelines
Cyanokit (hydroxocobalamin) increases systemic vascular resistance (SVR) in shock primarily through its nitric oxide scavenging properties, making it a valuable treatment option for vasodilatory shock states, including those associated with cyanide poisoning, as supported by the most recent guidelines 1. When administered, hydroxocobalamin binds directly to nitric oxide in the bloodstream, effectively removing this potent vasodilator from circulation. Nitric oxide normally causes blood vessel relaxation and dilation, so its removal leads to vasoconstriction and increased blood pressure. Additionally, hydroxocobalamin binds to hydrogen sulfide and peroxynitrite, which are also vasodilatory molecules. This multi-mechanism approach to vasoconstriction makes Cyanokit particularly useful in treating vasodilatory shock states.
The standard adult dose is 5g administered intravenously over 15 minutes, with a possible second 5g dose depending on clinical response, as part of the management of critical poisonings, including cyanide poisoning 1. This vasoconstrictive effect occurs rapidly after administration and can help stabilize blood pressure in critically ill patients while addressing the underlying cause of shock. The effect is generally transient but provides crucial time for implementing definitive treatments. It's worth noting that while other vasoactive agents like norepinephrine are commonly used in shock management 1, Cyanokit's unique mechanism of action makes it specifically beneficial for cases involving cyanide poisoning or other conditions where nitric oxide scavenging is advantageous.
In the context of shock management, it's crucial to follow the most recent guidelines, which emphasize the importance of early identification of sepsis, prompt administration of intravenous fluids, and the use of vasopressors as needed 1. However, the specific use of Cyanokit is guided by its efficacy in scavenging nitric oxide and its application in treating vasodilatory shock states associated with cyanide poisoning, as highlighted in the latest update from the American Heart Association 1.
Key points to consider in the use of Cyanokit for increasing SVR in shock include:
- Its mechanism of action through nitric oxide scavenging
- Its efficacy in treating vasodilatory shock states, particularly those associated with cyanide poisoning
- The standard adult dosing regimen
- The importance of integrating its use into a broader strategy for managing shock, including the administration of fluids and other vasopressors as necessary, based on the most current clinical guidelines 1.
From the Research
Mechanism of Action
- Hydroxocobalamin detoxifies cyanide by binding with it to form the renally excreted, non-toxic cyanocobalamin 2.
- The binding of hydroxocobalamin to cyanide does not form methemoglobin, allowing it to be used without compromising the oxygen-carrying capacity of hemoglobin 2.
Effects on Systemic Vascular Resistance (SVR)
- In a case report, a patient with cyanide poisoning was treated with hydroxocobalamin, and within 40 minutes of administration, vasopressors were discontinued, suggesting an increase in SVR 3.
- Another case report described a patient who ingested apricot kernels containing cyanide and was treated with hydroxocobalamin, resulting in normalized blood pressure and other hemodynamic parameters after 24 hours 4.
Clinical Evidence
- A prospective study of hydroxocobalamin for acute cyanide poisoning in smoke inhalation found that empiric administration of hydroxocobalamin was associated with survival among 67% of patients confirmed to have had cyanide poisoning 5.
- A case report described a patient with massive cyanide poisoning who was treated with a combination of hydroxocobalamin and sodium thiosulfate, resulting in no long-term neurological and visual sequelae 6.