High-Dose Hydroxocobalamin in Liver Transplantation: Effect on Blood Pressure and Risk of AKI

Background: High-dose hydroxocobalamin (CYANOKIT, HD-B12) is approved for cyanide poisoning and has recently been used in vasoplegic shock due to its vasoconstricting effects. However, studies evaluating the safety and efficacy of HD-B12 in vasoplegic shock are limited. HD-B12 use has been associated with oxalate nephropathy and acute kidney injury (AKI) following smoke inhalation, but the risk in other patient populations remains unexplored. Methods: We conducted a single-center retrospective study of patients undergoing liver transplantation from 2018 to 2023. The initial cohort included 664 patients, of which 191 were excluded due to dual organ transplant, need for pretransplant renal replacement therapy (RRT), or prior organ transplantation. We evaluated the effect of HD-B12 on blood pressure and the risk of AKI (stages II and III or the need for RRT) in liver transplant recipients. Results: A total of 473 patients were analyzed, including 52 who received HD-B12. The mean increase in mean arterial pressure (MAP) at 15, 40, and 60 minutes post-dose was 10.2 mmHg (p<0.001) (n=31), 9.1 mmHg (p = 0.004) (n=31), and 5.0 mmHg (p = 0.098) (n= 27), respectively. Of the 52 patients who received HD-B12, 29 (55.7%) developed AKI II, III, or required RRT within 7 days. In contrast, 92 (21.8%) patients who did not receive HD-B12 developed AKI II, III, or required RRT (OR 4.5; CI: 2.49–8.17; p<0.0001). Estimated blood loss (EBL) and hypotensive events were not significantly different between the groups. There was no difference in 90-day serum creatinine (p-t sCr). Conclusion: HD-B12 administration during liver transplantation increased MAP by approximately 10 mmHg within 15 to 40 minutes, but it was also associated with a significantly higher risk of AKI and needing RRT. Other known risk factors for AKI during liver transplantation, such as EBL and hypotensive events, did not differ between groups, suggesting that the increased rate of AKI in the HD-B12 group is not secondary to these traditional factors. Given reports of oxalate nephropathy and AKI in burn patients, this mechanism may also be at play here. This off-label use of HD-B12 warrants further investigation.