Which medications are used in the treatment of cyanide toxicity?

Updated: May 30, 2020
  • Author: Inna Leybell, MD; Chief Editor: Michael A Miller, MD  more...
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Oxygen is the initial agent used in suspected or confirmed cyanide poisoning. Sodium bicarbonate is used in patients with severe poisoning that has produced marked lactic acidosis. Epinephrine is used to support cerebral and coronary perfusion in low-flow states.

Antidotal therapy is indicated for any patient in whom the diagnosis of cyanide toxicity is considered on clinical grounds, even before laboratory confirmation. Activated charcoal can be used in patients presenting after ingestion of cyanide salts or organic cyanides.

Anticonvulsants are used as indicated. Lorazepam is the drug of choice; midazolam and phenobarbital are second-line agents.

Cyanide antidotes are the key medications for hydrogen cyanide (HCN) poisoning. Hydroxocobalamin (HCO, vitamin B-12) is the first-line therapy for cyanide toxicity. It functions by binding cyanide to its cobalt ion to form cyanocobalamin, which is essentially nontoxic and is cleared renally. [38, 35] HCO can be combined with sodium thiosulfate for accelerated detoxification. Amyl nitrite is an alternative temporizing therapy; it may be useful in the absence of intravenous (IV) access (eg, in industrial settings).

Sodium thiosulfate enhances the conversion of cyanide to thiocyanate , which is renally excreted. Thiosulfate has a somewhat delayed effect and thus is typically used with sodium nitrite for faster antidote action. Sodium nitrite must be used with caution because it may result in significant hypotension and cardiovascular collapse, in addition to generating dangerous levels of methemoglobin. However, in cases of smoke inhalation in which cyanide toxicity is suspected, administration of sodium thiosulfate is safe.

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