The newest antidote for cyanide poisoning, hydroxocobalamin, has several advantages over the older Cyanide Antidote Kit (amyl nitrite, sodium nitrite, sodium thiosulfate). Hydroxocobalamin works rapidly, does not induce methemoglobinemia, and does not cause vasodilation/hypotension.
Two noteworthy adverse effects were noted in human volunteer studies:
- The first is self-limiting hypertension. However, think about the patient population you are treating. They are most likely hypotensive from the cyanide/carbon monoxide poisoning. Increased blood pressure is a welcome adverse effect in these cases.
- The second is red discoloration of the skin and urine, secondary to the red color of hydroxocobalamin (see attached picture). This effect can be quite pronounced, especially if you aren’t prepared for it. There is no harm to the patient although it can last up to 8 days.
Bottom line: Adverse effects occur with hydroxocobalamin administration but are not anything to be concerned about, especially considering the toxin you are treating.
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References
Uhl W, Nolting A, Golor G, Rost KL, Kovar A. Safety of hydroxocobalamin in healthy volunteers in a randomized, placebo-controlled study. Clin Toxicol 2006;44:S17-S28.