Which substance is administered in cases of cyanide poisoning?

In cases of cyanide poisoning, sodium nitrite is administered because it acts as an important antidote. The mechanism of action involves the conversion of hemoglobin to methemoglobin, which can then bind to cyanide and help mitigate its toxic effects. Methemoglobin has a greater affinity for cyanide compared to cytochrome enzymes, thus sequestering the cyanide and facilitating its elimination from the body.

Sodium thiosulfate is commonly used in combination with sodium nitrite; it helps to detoxify cyanide by converting it to thiocyanate, which is less toxic and can be excreted in urine. Calcium gluconate is typically used to treat hypocalcemia and does not have a role in cyanide poisoning. Activated charcoal is used in some cases of poisoning to absorb toxins from the gastrointestinal tract but is not effective once cyanide has entered the bloodstream or in cases of respiratory distress. This makes sodium nitrite the primary choice in the acute treatment of cyanide toxicity.