If the preferred cyanide antidote is not available, what can be used?

In cases of cyanide poisoning, if the preferred antidote, such as hydroxocobalamin or sodium thiosulfate, is not available, using a combination of oxygen and nitrites, commonly referred to as V (for sodium nitrite) and G (for sodium thiosulfate or another supportive treatment), can be the next best option.

Sodium nitrite works by converting hemoglobin into methemoglobin, which has a higher affinity for cyanide, effectively reducing the amount of free cyanide available to bind to the cytochrome c oxidase enzyme in the mitochondria. This helps to alleviate the toxic effects of cyanide in the body. Sodium thiosulfate acts as a substrate for the enzyme rhodanese, facilitating the conversion of cyanide to the less toxic thiocyanate, which can be excreted in urine.

Choosing this combination can significantly improve outcomes in a scenario where specific cyanide antidotes are unavailable, making it a vital option in cyanide poisoning management.