Cyanide poisoning antidotal treatment

Amyl nitrate is an effective antidote against cyanide poisoning. The treatment involves artificial respiration, followed by inhalation of amyl nitrite. In severe poisoning, intra-venons administration of sodium nitrite, followed by sodinm thiosnlfate is given. The dose is 0.3 g of NaN02 (10 mL of a 3% solution at a rate of 2-5 mL/min) and 25 g of Na2S203 (50 mL of a 25% solution at a rate of 2-5 mL/min) (Hardy and Boylen 1983). 

Treatment — Patients should be decontaminated immediately prior to treatment using the decontamination method presented in Section 7.3.3. The Lilly Cyanide Antidote Kit contains amyl nitrite, sodium nitrite, and sodium thiosulfate. Dimeth-ylaminophenol, cobalt-edetate, or vitamin B12a are alternative antidotes for cyanide poisoning.5... 

Treatment of cyanide poisoning includes rapid administration of activated charcoal (although charcoal binds cyanide poorly, it can reduce absorption) and general supportive care. The conventional antidote kit available in the USA includes two forms of nitrite (amyl nitrite and sodium nitrite) and sodium thiosulfate. The nitrites induce methemoglobinemia, which binds to free CI T creating the less toxic cyanomethemoglobin thiosulfate is a cofactor in the enzymatic conversion of CN to the much less toxic thiocyanate (SCINT). Recently, the FDA approved a concentrated form of hydroxocobalamin, which is now available as the Cyanokit (EMD Pharmaceuticals, Durham, North Carolina). Hydroxocobalamin (one form of vitamin B12) combines rapidly with CN to form cyanocobalamin (another form of vitamin B12). 

The only pharmacological use of vitamin B12, other than for the treatment of deficiency or for rare children with vitamin dependency diseases affecting the binding of the coenzyme to methylmalonyl CoA mutase (Section 10.8.2), is as an antidote for cyanide poisoning. Supplements of vitamin B12 are available for strict vegetarians who might be at risk of deficiency. There is no evidence of any adverse effects of high intakes of vitamin B12. 

Thankfully, the body has a detoxication system for cyanide, presumably because of the presence of naturally occurring cyanides in plants. This defence mechanism, however, can be easily overwhelmed and fatalities do occur (see p. 220). If someone working with a cyanide is found frothing a little around the mouth, an unusually brighter red colour than normal, and smelling of bitter almonds (a bit like marzipan), all is not lost, however. If they are still ahve, there is hope, for there are several antidotes and treatments for cyanide poisoning. Unfortunately, not everyone can smell cyanide as there appears to be a genetic deficiency in some people which means that they cannot detect it by its smell. 

Patients who are critical and do not satisfactorily respond to supportive therapy should be administered specific cyanide antidotes as outlined in Table 19.5. Cyanide antidotes have been classified into three main groups based on their mechanism of action (1) methemoglobin inducers, (2) sulfur donors, and (3) cobalt compounds. The definitive treatment of cyanide poisoning differs in various countries due to different medical practices and guidelines. The safety... 

Marrs, T.C. (1988). Antidotal treatment for acute cyanide poisoning. Adverse Drug React. Acute Poisoning Rev. 4 179-206. 

Megarbane, B., Delahaye, A., Goldgran-Toledano, D., Baud, F.J. (2003). Antidotal treatment of cyanide poisoning. J. Chin. Med. Assoc. 66 193-203. 

Cyanide antidote. The immediate administration of nitrite is a highly effective treatment for cyanide poisoning. What is the basis for the action of this antidote (Hint Nitrite oxidizes ferrohemoglobin to ferrihemoglobin.)... 

Antidotes Used Clinically in the Treatment of Human Acute Cyanide Poisoning... 

Marrs TC (1988). Antidotal treatment of acute cyanide poisoning. Adv Drug Reacti Acute Poison Rev, 4, 178-206. 

Thompson JP (2004). The use of antidotes in the emergency treatment of cyanide poisoning. Clin Toxicol, 42,411. 

Delayed ischaemic anoxia may also result from cyanide poisoning as a result of circulatory effects. There are several antidotal treatments, but the blood level of cyanide should be determined if possible as treatment may be hazardous in some cases. Cyanide is metabolized in the body, indeed up to 50% of the cyanide in the circulation may be metabolized in 1 h. This metabolic pathway involves the enzyme rhodanese and thiosulphate ion which produces thiocyanate (figure 7.461. However, the crucial part of the treatment is to reduce the level of cyanide in the blood as soon as possible and allow the cyanide to dissociate from the cytochrome oxidase. This is achieved by several means. Methaemoglobin will bind cyanide more avidly than cytochrome oxidase and therefore competes for the available cyanide. 

Possibly the most important elements of therapy are general supportive actions, which, by themselves, can effect the recovery of most casualties without further risk from specific antidotal therapy.41 They are probably the only indicated therapies for casualties of cyanide poisoning who arrive conscious at the emergency medical treatment station. 

Cyanide poisoning is treated with specific antidotes and supportive medical care in a hospital setting. The most important thing is tor victims to seek medical treatment as soon as possible. 

B. Specific drugs and antidotes, if cyanide poisoning is suspected, administer sodium thiosulfate (see p 505). Sodium nitrite treatment may aggravate hypotension and should not be used. Hydroxocobalamin (p 453), 25 mg/h IV infusion, is sometimes coadministered with high-dose nitropmsside as prophylaxis against cyanide toxicity. 

I. Pharmacology. Hydroxocobalamin and cyanocobalamin are synthetic forms of vitamin B.,2 used for the treatment of pernicious anemia. Hydroxocobalamin has been recognized as an antidote for cyanide poisoning for over 40 years. Hydroxocobalamin immediately exchanges its hydroxyl group with free cyanide in the plasma to produce the nontoxic cyanocobalamin. When administered to patients with cyanide poisoning, it Improves heart rate, systolic blood pressure, and acidemia. In normal individuals, hydroxocobalamin has a plasma half-life of 3-20 hours. In patients with cyanide poisoning, the haif-life is 14-24 hours, and the complexed compound, cyanocobalamin, has a half-life of 6-12 hours. 

Ten Eyck RP, Schaerdel AD, Ottinger WE. 1986. Comparison of nitrate treatment and stroma-free methemoglobin solution as antidotes for cyanide poisoning in a rat model. Journal of Toxicology and Clinical Toxicology 23 477-487. 

TLV equals that of cyanides. Spedid first aid required in the event of poisoning antidotes must be available (with instructions). Special treatment administer oxygen (100%) if necessary, avoid mouth-to-mouth resuscitation if possible (risk to person assisting). Unbreakable packaging preferred if breakable, ke In unbieakable container. 

Poison Treatment As discussed previously, methemoglobin binds well and competes with cytochrome oxidase for cyanide ions. Consequently, the antidote developed for cyanide poisoning involves increasing the formation of methemoglobin in the blood, by inhalation of amyl nitrate vapor (Chen 1952). Antidote kits contain amyl nitrate ampoules. To administer the antidote, the ampoule is broken in a cloth such as a handkerchief and held close to the victim s nose while artificial respiration is being conducted. Resuscitation by mouth is not recommended a mechanical resuscitator should be used instead. If the victim does not respond to the amyl nitrate treatment, a medical professional would then increase the methemoglobin production by intravenous injection of sodium nitrate followed by administration of thiosulfate to increase the activity of the rhodanese enzyme. 

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