Cyanide has several antidotes, with differing mechanisms of action and diverse toxicological, clinical, and risk-benefit profiles. The international medical community lacks consensus about the
antidote or antidotes with the best risk-benefit ratio. Critical assessment of
cyanide antidotes is needed to aid in therapeutic and administrative decisions that will improve care for victims of
cyanide poisoning (particularly
poisoning from enclosed-space fire-
smoke inhalation), and enhance readiness for
cyanide toxic terrorism and other mass-casualty incidents. This paper reviews preclinical and clinical data on available
cyanide antidotes and considers the profiles of these antidotes relative to properties of a hypothetical ideal
cyanide antidote. Each of the antidotes shows evidence of efficacy in animal studies and clinical experience. The data available to date do not suggest obvious differences in efficacy among antidotes, with the exception of a slower onset of action of
sodium thiosulfate (administered alone) than of the other antidotes. The potential for serious toxicity limits or prevents the use of the
Cyanide Antidote Kit,
dicobalt edetate, and
4-dimethylaminophenol in prehospital empiric treatment of suspected
cyanide poisoning.
Hydroxocobalamin differs from these antidotes in that it has not been associated with clinically significant toxicity in antidotal doses.
Hydroxocobalamin is an
antidote that seems to have many of the characteristics of the ideal
cyanide antidote: rapid onset of action, neutralizes
cyanide without interfering with cellular
oxygen use, tolerability and safety profiles conducive to prehospital use, safe for use with
smoke-inhalation victims, not harmful when administered to non-poisoned patients, easy to administer.