![]() Based on the limited efficacy data available, as well as the more widely documented safety data, hydroxocobalamin is a safe and effective first-line antidote for cyanide toxicity and has been demonstrated to be efficacious in patients with cyanide poisoning with whole blood cyanide levels up to 150 μmol/L. In cases of ingestion of cyanide with suicidal intent (where blood cyanide levels may be >150 μmol/L or plasma lactate concentrations >20 μmol/L), the usual dose of 5–10 g may be insufficient. At higher blood cyanide concentrations, there is little further rise in plasma cyanocobalamin and it is suggested that the rate-limiting step in the formation of cyanocobalamin is the availability of antidote, not the absence of cyanide ions. The amount of cyanocobalamin formed after a dose of 5 g hydroxocobalamin correlates linearly until a blood cyanide level of 40 μmol/L is reached. As the half-life of cyanide in smoke inhalation victims is calculated to be between 1.2 and 3.0 hours, it is suggested that hydroxocobalamin can be satisfactorily used as single-dose therapy. The half-life of hydroxocobalamin in cyanide-exposed patients is 26.2 hours. Hydroxocobalamin and cyanocobalamin are excreted by the kidney. In Australian it is approved for use under the Special Access Scheme. Antidotal doses of hydroxocobalamin are approximately 5000 times the physiological dose. It complexes with cyanide, on a mole-for-mole ratio, to form cyanocobalamin. It is the cyanide antidote most widely used in Europe. With an understanding of these concepts, you too, will be able to treat that secret agent who is trying to kill himself (or herself) before they reveal the secret plans.Peter Cameron MBBS MD FACEM, in Textbook of Adult Emergency Medicine, 2020 Specific cyanide antidotes ( Table 25.13.1) Hydroxocobalamin (Cyanokit)Ī systematic review of cyanide poisoning management for the Australian Resuscitation Council has recommended this as the initial antidote for the management of adults with suspected severe cyanide poisoning. This is complicated by the lack of a readily available assay and the variability of available antidotes. The management of cyanide poisoning requires firstly the identification of patients who may be at risk of cyanide poisoning and the selection of antidotes. Hydroxocobalamin is widely used in Europe but only has limited availability in North America and Australia. In North America amyl nitrate pearls for inhalation can also used be used. In Australia dicobalt edetate IV, sodium nitrite IV and sodium thiosulfate are available. The availability of antidotes to cyanide poisoning varies around the world. Another source of cyanide includes the combustion of wool, silk, synthetic rubber and polyurethane. Deliberate contamination of medications and food has occurred recently. Suicides are the commonest cause of cyanide poisoning. Industries that use cyanide include metal extraction and refining, electroplating, photography and fumigation. It is important to know the unique mechanism of action of this poison as delay in treatment can have disastrous consequences to the patient. It is used in many chemical compounds including medications and can be found endogenously in plant and bacteria. ![]() Its toxicity was soon discovered by Scheele who, upon breaking the flask of his newly found fluid, was killed by the resulting vapours.Ĭyanide is a rapidly toxic agent that is found in liquid and gaseous form. ![]() Hydrogen cyanide was not isolated in a pure form until 1786 when Scheele extracted it from the dye Prussian blue.
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