The pharmacology & toxicology of cyanide & its derivatives

Cyanides are utilized in many industrial applications including preparation of chemical intermediates, electroplating, and mining. Cyanide has been utilized in chemical warfare operations as well. Cyanide is also synthesized and found in plants and animals including man where it is thought to perform multiple functions. A variety of enzymes are known to detoxify cyanide under different conditions. These include rhodanese, 3-mercaptopyruvate-sulfur transferase, thiosulfate reductase, cystathionase and albumin. Cyanide appears to exert its toxic effect primarily by inhibiting cytochrome oxidase although other enzymes are also inhibited. Therapeutic antagonist categories to treat cyanide include methemoglobin formers such as nitrite, sulfane-sulfur donors such as thiosulfate, metal salts or complexes such as cobalt and cyanohydrin-forming compounds such as dihydroxyacetone or alpha keto-glutaric acid. Advantages and disadvantages of each category will be discussed. Newer compounds under development have been found that may allow for prophylactic therapy for cyanide poisoning with minimal side effects. In addition, portable co-oximetry devices may provide real-time measurement of cyanide in field units.