Which of the following is a cyanide antidote?

The correct antidote for cyanide poisoning among the given options is nitrite. Nitrite works by inducing the formation of methemoglobin, which has a higher affinity for cyanide than cytochrome c oxidase, the enzyme affected by cyanide. This allows methemoglobin to bind with cyanide, thereby preventing it from causing cellular damage and facilitating its conversion to a less toxic form that can be eliminated from the body.

When treated with nitrite, the body can effectively reduce the levels of active cyanide, helping to mitigate its toxic effects. This mechanism is crucial, especially in emergency situations where rapid intervention is necessary to prevent severe outcomes from cyanide exposure.

Other options, while related to cyanide treatment, do not directly act as primary antidotes. For instance, cyanocobalamin is a form of vitamin B12, which is sometimes used as a secondary treatment after nitrite therapy but is not the initial antidote for cyanide poisoning. Amyl nitrite, similar to nitrite, can also induce methemoglobinemia, but it is not used as commonly due to its less effective and less controllable administration. Sodium thiosulfate acts as a secondary treatment by providing a sulfur donor to bind cyanide and facilitate