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Deaths Due to Asphyxiant Gases
Published in Sudhir K. Gupta, Forensic Pathology of Asphyxial Deaths, 2022
Sodium nitrite is given intravenously to increase the content of methemoglobin. Cyanide preferentially bind to the ferric iron of methemoglobin to form cyanmethemoglobin, i.e., methemoglobin prevents the cyanide to combine to the cytochrome and enabling the mitochondria to reactivate electron transport. Sodium thiosulfate, the third component of the cyanide antidote kit, has poor penetration into the mitochondria that leads to its slow onset of action. It act as sulfhydryl donor. Transfer of sulfur from thiosulfate to the cyanide ion is done by rhodanese (sulphtransferase), a mitochondrial enzyme that is present in abundance in our body.15
CBRN and the Trauma Victim
Published in Ian Greaves, Keith Porter, Jeff Garner, Trauma Care Manual, 2021
Ian Greaves, Keith Porter, Jeff Garner
These include oxygen, respiratory support and, where appropriate, cyanide antidotes including sodium nitrite/thiosulphate and cobalt-chelation therapy (including hydroxocobalamin). The management of hydrogen sulphide (H2S) poisoning is sodium nitrite and oxygen. Sodium nitrite for cyanide and H2S poisoning is used with the intention of causing a MetHb level of ~30% in order to dissociate the poison from the mitochondria and back into the intravascular compartment. It should, however, be avoided in cases of trauma (haemorrhage) or carbon mon-oxide (CO) poisoning.
Battlefield Chemical Inhalation Injury
Published in Jacob Loke, Pathophysiology and Treatment of Inhalation Injuries, 2020
Postexposure therapy consists of the following. Remove the subject from the contaminated environment immediately. Amyl nitrite (pearls, ampules), one or two crushed and held near nose/mouth for inspiration repeated every 5 min (to a maximum of eight ampules until recovery). Apneic individuals should immediately receive artificial respiration (possibly with a device to administer amyl nitrite via one-way valve). Oxygen therapy should be added immediately if available. Moderate hypotension may occur with this therapy but is rarely of clinical significance. Sodium nitrite/thiosulfate is then administered: parenteral injection of 10 ml 3% sodium nitrite solution over 1 min followed with 50 mil 25% sodium sulfate solution over 5 min. As part of the post-acute therapy, individuals should be observed for evidence of hypoxic damage (Norris et al., 1984) to critical organs. There is no evidence that antioxidants or antiinflammatory agents are of specific value. Individuals who survive (without coma or convulsions) an exposure for the time necessary to begin parenteral therapy are very likely to have survived without such therapy. This therapy is primarily indicated for other than inhalational exposures where absorption may continue over a prolonged period (e.g., swallowed CN salts, severe dermal/ocular exposure).
A comprehensive review of treatments for hydrogen sulfide poisoning: past, present, and future
Published in Toxicology Mechanisms and Methods, 2023
Cristina Santana Maldonado, Abigail Weir, Wilson K. Rumbeiha
Hyperbaric oxygen has been used for years and remains a valuable tool for severe cases of H2S poisoning (Lindenmann et al. 2010; Price et al. 2021). However, the technique is only valuable for treating individual cases as this equipment is not widely available. It is not ideal for the treatment of mass casualties. Hyperbaric oxygen increases oxygen plasma diffusion which leads to improved oxygenation of tissue (Smilkstein et al. 1985; Whitcraft et al. 1985). Although there is no FDA-approved drug for H2S toxicity, certain antidotes have been used in cases of poisoning in a hospital setting. Much like inhaled cyanide, it is suggested to use inhaled nitrite therapy, specifically amyl nitrite, for 30 seconds every minute until the intravenous (IV) line is started. Once IV is introduced, sodium nitrite is given intravenously. Early citations of sodium nitrite therapy suggested clinical efficiency (Hall and Rumack 1997). Recently, however, nitrite therapy has become a controversial topic as the efficacy of nitrite therapy in H2S victims remains inconsistent (Baud et al. 2018). The H2S metabolite thiosulfate and antioxidants have also been used to treat H2S poisoning victims with little success.
Methyl mercaptan gas: mechanisms of toxicity and demonstration of the effectiveness of cobinamide as an antidote in mice and rabbits
Published in Clinical Toxicology, 2022
George P. Philipopoulos, John Tat, Adriano Chan, Jingjing Jiang, David Mukai, Tanya Burney, Melody Doosty, Sari Mahon, Hemal H. Patel, Carl W. White, Matthew Brenner, Jangwoen Lee, Gerry R. Boss
Sodium nitrite, sodium thiosulfate, and hydroxocobalamin are effective in treating cyanide poisoning in animals and humans, and some studies suggest hydroxocobalamin is effective against hydrogen sulfide poisoning [4,19–26]. However, it is unknown whether these drugs could be used against CH3SH poisoning. Sodium nitrite generates methemoglobin, which scavenges cyanide, but methemoglobinemia reduces oxygen carrying capacity of blood and nitrite can cause hypotension [27–29]. Sodium thiosulfate acts against cyanide by serving as a substrate for rhodanese to convert cyanide into thiocyanate [30], but thiosulfate would unlikely be helpful against CH3SH poisoning. Hydroxocobalamin binds cyanide and hydrogen sulfide [31,32], but it is unknown if it also binds CH3SH, and it must be administered in large volumes via intravenous infusion.
Development of sodium tetrathionate as a cyanide and methanethiol antidote
Published in Clinical Toxicology, 2022
Adriano Chan, Jangwoen Lee, Subrata Bhadra, Nesta Bortey-Sam, Tara B. Hendry-Hofer, Vikhyat S. Bebarta, Sari B. Mahon, Matthew Brenner, Brian Logue, Renate B. Pilz, Gerry R. Boss
Cyanide is a well-known toxic chemical. It is generated as hydrogen cyanide gas in structural fires and is a major contributor to death by smoke inhalation [1]. It is used in a variety of industries, with over three billion pounds of cyanide salts produced annually worldwide [2]. It has the potential to be released by terrorists and is considered a high-priority chemical threat by the Center for Disease Control. Currently approved treatments for cyanide poisoning in the United States are hydroxocobalamin and the combination of sodium nitrite and sodium thiosulfate. Both treatments must be given intravenously over 10–15 min, which would not be practical in the setting of a major fire, industrial accident, or terrorist attack. A treatment is needed that can be given quickly, for example by intramuscular injection using an autoinjector. This requires that the drug is sufficiently potent and soluble that it can be administered in a small volume.