Comparison of nitrite treatment and stroma-free methemoglobin solution as antidotes for cyanide poisoning in a rat model.

The standard nitrite/thiosulfate regimen for cyanide poisoning was tested in our rat model. By modifying the treatment regimen and the nitrite solution an effective antidote against an LD90 of cyanide could be produced. However, this treatment was effective against two times the LD90 only when administered ten minutes prior to cyanide injection. These results are in marked contrast to our results with stroma-free methemoglobin solutions (SFMS) which showed SFMS to be a highly effective antidote against four times the LD90 when administered 30 seconds after an intravenous injection of cyanide. SFMS proved to be an effective antidote for two times the LD90 when administered up to sixty seconds after the cessation of respiration.