Which treatment is recommended for cyanide poisoning if available?

• A. Administer methylene blue.
• B. Administer sodium nitroprusside.
• C. Administer hydroxocobalamin.
• D. Administer EDTA chelation therapy.

Answer: (C)

Cyanide poisoning prevents cells from using oxygen because cyanide blocks the enzyme that drives cellular respiration, so tissues become hypoxic even when oxygen is present. The antidote works by binding the cyanide and converting it into a form the body can safely excrete. Hydroxocobalamin does exactly this: it binds cyanide to form cyanocobalamin (a normal form of vitamin B12) that is then eliminated by the kidneys. This rapid, targeted action makes it the preferred treatment if available, helping restore cellular respiration quickly.

Methylene blue is used for methemoglobinemia, not cyanide poisoning, so it doesn’t address the underlying problem. Sodium nitroprusside can release cyanide during metabolism, potentially worsening the situation rather than treating it. EDTA chelation therapy is useful for heavy metal poisoning, not cyanide.