An interim analysis was conducted after 15 of the initially planned 18 animal protocols were completed (seven MB and eight NE). This revealed that, for the primary outcome, MB was clearly not superior to NE. Furthermore, it would be impossible to achieve a statistically significant effect for the MB hazard ratio with the addition of three pigs, regardless of the outcome. Therefore, the study was terminated early. Overall, one of seven animals (14 percent) in the MB group survived to 300 minutes compared to two of eight animals (25 percent) in the NE group. Median survival time was 100 minutes for the MB group and 177 minutes for the NE group. Survival time did not differ by group (log-rank test P=0.29), but there was a nonsignificant trend toward longer survival in the NE group.

Projected Impact

Our data contribute to a growing body of literature on usage of methylene blue in toxin-induced shock. We hope that this will encourage more research in the field as it is still unclear where this antidote fits in the management of patients.

Dr. LeRoy is an attending emergency physician and clinical toxicologist at Regions Hospital in St. Paul, Minnesota, and assistant professor of emergency medicine at the University of Minnesota Medical School.