Antidotes for cyanide poisoning
| Order | Antidote | Dose | Side effects | Comments |
|---|---|---|---|---|
| 1st line | Amyl nitrite | Crushable perles, vapour inhaled, either directly or via a bag and mask | Methaemoglobinaemia Vasodilatation Headache | The mechanism of action of amyl nitrite is unclear but may relate to its action as a vasodilator |
| 1st line | Sodium thiosulphate | 412.5 mg/kg (1.65 ml/kg of 25% solution), maximum 50ml, give over 10 minutes | Nausea Vomiting Muscle cramps Arthralgia | Combines with CN to form thiocyanate; this is non-toxic and excreted in the urine |
| 2nd line | Sodium nitrite | 0.33 ml/kg of 3% solution, maximum 10 ml, over 4 minutes | Potentially fatal methaemoglobinaemia, avoid excessive dose, keep metHb at about 20% | See amyl nitrite. For moderate to severe poisoning, do not use as prophylaxis |
| 2nd line | Dicobalt EDTA | 4 mg/kg over 1 minute, followed by 50 ml 50% dextrose | In the absence of cyanide, cobalt toxicity can be severe Anaphylaxis | Chelates cyanide and does not produce metHb. For moderate to severe poisoning, do not use as prophylaxis |