From the Guidelines
Hydroxocobalamin reacts with cyanide to form cyanocobalamin (vitamin B12), a stable and non-toxic compound. This reaction is the basis for using hydroxocobalamin as an antidote for cyanide poisoning, as it effectively neutralizes the toxic effects of cyanide by binding to it and forming a stable compound that can be safely excreted in urine 1. The mechanism involves hydroxocobalamin's cobalt ion, which has a higher binding affinity for cyanide than cytochrome c oxidase does, thereby preventing cyanide from inhibiting cellular respiration and causing cell death 1. Some key points to consider when using hydroxocobalamin for cyanide poisoning include:
- Hydroxocobalamin is the primary recommended treatment for patients with suspected cyanide poisoning, especially in cases of smoke inhalation where simultaneous carbon monoxide poisoning is a concern 1.
- The typical dose of hydroxocobalamin is 5g (70 mg/kg in adults) administered as an intravenous infusion over 15 minutes, with a second dose possible depending on the severity of poisoning.
- Hydroxocobalamin is preferred over sodium nitrite and sodium thiosulfate due to its wider indications, ease of use, and anticipated safety in widespread use 1. Overall, the use of hydroxocobalamin to form cyanocobalamin is a critical component of treating cyanide poisoning, and its effectiveness and safety make it a preferred antidote in emergency situations 1.
From the FDA Drug Label
Hydroxocobalamin shares the cobalamin molecular structure with cyanocobalamin. The stable compound formed by the reaction between hydroxocobalamin and cyanide is cyanocobalamin.
- The reaction involves the replacement of the hydroxyl group in hydroxocobalamin with a cyanide ion, resulting in the formation of cyanocobalamin. 2
From the Research
Reaction Between Hydroxocobalamin and Cyanide
- The reaction between hydroxocobalamin and cyanide forms a stable compound known as cyanocobalamin 3.
- This compound is formed when hydroxocobalamin combines with cyanide, effectively binding and detoxifying the cyanide ions.
- The formation of cyanocobalamin is highly correlated with the initial blood cyanide concentration, indicating that hydroxocobalamin is an effective antidote for cyanide poisoning 3.
Properties of the Stable Compound
- Cyanocobalamin is a stable compound that is formed through the reaction between hydroxocobalamin and cyanide.
- The stability of this compound allows it to be used as a marker for the amount of cyanide present in the body, and its formation can be used to gauge the severity of exposure and evaluate the adequacy of treatment 3.
- The compound has been shown to be effective in reducing cyanide concentrations in controlled studies of nitroprusside therapy and in heavy smokers 4.
Clinical Relevance
- Hydroxocobalamin is an attractive antidote for cyanide poisoning due to its ability to bind and detoxify cyanide ions 5.
- The efficacy of hydroxocobalamin in human cyanide poisoning has been demonstrated in several studies, although more research is needed to fully understand its effects 6, 4, 5.
- Hydroxocobalamin has been shown to be safe and well-tolerated in patients with suspected cyanide poisoning, with few adverse events reported 7.