What is the recommended dosing for Cyanokit (hydroxocobalamin) in the treatment of vasoplegia?

Hydroxocobalamin (Cyanokit) Dosing for Vasoplegia

For vasoplegia syndrome, hydroxocobalamin should be administered as an initial dose of 5 g intravenously over 15 minutes, with the option to extend the infusion over 6 hours for more sustained hemodynamic effects. 1, 2

Dosing Recommendations

• Initial dose: 5 g IV (standard dose used for cyanide toxicity) administered over 15 minutes for immediate hemodynamic improvement in refractory vasoplegia 1, 2
• For more sustained effect: Consider extended duration infusion of 5 g administered over 6 hours 1, 3
• Additional dosing may be required based on hemodynamic response and vasopressor requirements 4

Clinical Response Patterns

• Response patterns to hydroxocobalamin in vasoplegia vary significantly among patients 4:
  • Responders (24% of patients): Show brisk mean arterial pressure (MAP) increase >15 mmHg sustained for >60 minutes with 50% vasopressor reduction 4
  • Poor responders (27% of patients): Minimal hemodynamic response despite continued vasopressor support, often with higher baseline mortality risk 4
  • Sustainers (27% of patients): Sustained MAP improvement without significant rebound 4
  • Rebounders (21% of patients): Initial hypertensive overshoot followed by MAP decrease 4

Monitoring and Considerations

• Monitor mean arterial pressure continuously before and after administration 4, 5
• Track vasopressor requirements (norepinephrine-equivalent rates) 5 minutes prior to and up to 60 minutes following administration 4
• Be prepared to rapidly reduce vasopressor doses in responders to avoid hypertensive overshoot 5, 2
• Expect chromaturia (red-colored urine) as a common and benign side effect 5
• The hemodynamic improvement from bolus administration typically persists for only a few hours, which may necessitate extended infusion strategies 1, 3

Clinical Scenarios for Use

• Refractory vasoplegia post-cardiopulmonary bypass unresponsive to multiple vasopressors 1, 4
• Vasoplegic syndrome during liver transplantation refractory to high-dose vasopressors and methylene blue 2
• Nimodipine-induced refractory vasoplegia in subarachnoid hemorrhage 5

Common Pitfalls and Caveats

• Hydroxocobalamin use for vasoplegia is currently off-label 1
• Response heterogeneity may depend on patient preoperative condition and timing of administration 4
• Extended infusion may provide more sustained vasopressor reduction compared to bolus dosing (NEE AUC was significantly higher in the bolus group) 3
• No controlled clinical trials have definitively established efficacy, though case series show promising results 1, 4