Concept

Ethyl carbamate

Résumé
Ethyl carbamate (also called urethane) is an organic compound with the formula CH3CH2OC(O)NH2. It is an ester of carbamic acid and a white solid. Despite its name, it is not a component of polyurethanes. Because it is a carcinogen, it is rarely used, but naturally forms in low quantities in many types of fermented foods and drinks. It is produced industrially by heating urea and ethyl alcohol. It arise also by the action of ammonia on ethyl chloroformate. Ethyl carbamate has been used as an antineoplastic agent and for other medicinal purposes, but this application ended after it was discovered to be carcinogenic in 1943. However, Japanese usage in medical injections continued and from 1950 to 1975 an estimated 100 million 2 ml ampules of 7-to-15% solutions of ethyl carbamate were injected into patients as a co-solvent in water for dissolving water-insoluble analgesics used for post-operation pain. These doses were estimated to be at levels that are carcinogenic in mice. This practice was stopped in 1975. "This regrettable medical situation appears to have involved the largest number (millions) of humans exposed to the largest doses of a pure carcinogen that is on record". The author, U.S. cancer researcher James A. Miller, called for studies to determine the effects on Japanese cancer rates to be performed but apparently none were ever done. Prior to World War II, ethyl carbamate saw relatively heavy use in the treatment of multiple myeloma before it was found to be toxic, carcinogenic, and largely ineffective. By US FDA regulations, ethyl carbamate has been withdrawn from pharmaceutical use. However, small quantities of ethyl carbamate are also used in laboratories as an anesthetic for animals. Ethyl carbamate was reclassified as a Group 2A carcinogen by IARC in 2007. Ethyl carbamate is frequently used as an anaesthetic in animal experiments, with more than 100 animal studies using ethyl carbamate published each year. One advantage of using ethyl carbamate is that it has a very long duration of action, with some adult rats remaining anaesthetised 24 hours after administration of the drug.
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