Cyanokit (hydroxocobalamin, a form of vitamin B12) is an injectable therapy most often used to treat cyanide toxicity. This medication readily combines with cyanide to form cyanocobalamin thereby freeing cytochrome c oxidase to proceed with aerobic respiration in the electron transport chain.
As a cardiothoracic anesthesiologist, I’ve used Cyanokit to treat profound vasoplegia refractory to conventional vasopressors on cardiopulmonary bypass (CPB). The dysregulation of nitric oxide (NO), a potent vasodilator, has been implicated in this form of vasoplegia. In the absence of cyanide, Cyanokit binds nitric oxide to mitigate its vasodilatory effects.
Although methylene blue acts via a similar mechanism, it can precipitate serotonin syndrome with associated autonomic and neuromuscular instability. If a patient is not on an antidepressant that involves the serotonergic pathway, I’ll often start with methylene blue and escalate to Cyanokit (> $10,000 per dose at the time of this writing). Also keep in mind that if a patient received Cyanokit and requires intermittent hemodialysis (iHD), the blood leak detector may be triggered not permitting iHD to proceed.
Drop me a comment below with questions! 🙂
Given the paucity of evidence of hydroxocobalamin for refractory vasoplegia, where do you start with your dosing and do you have thresholds to redose?
As you alluded to, there’s really nothing I’m aware of to guide redosing. I just run the whole bottle slowly on bypass.
Appreciate the reply! Trying to come up with a refractory vasoplegia algorithm for our surgeons. I also wonder if we may be waiting too long to reach for these “refractory” therapies and missing the boat on preserving the microvasculature with these antioxidants.
Definitely an interesting area to research further! 🙂