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a colorless, liquid chelating agent used in the treatment of heavy metal poisoning; it forms a relatively stable compound with arsenic, mercury, gold, and certain other metals, thus protecting the vital enzyme systems of the cells against the effects of the metals. It is sometimes diluted with water and used to wash the stomach, with some of the solution being left in the stomach. Side effects include tachycardia, hypertension, nausea and vomiting, severe headaches, and a sense of constriction of the chest; barbiturates are usually ordered to relieve the symptoms, which should subside within an hour. Dimercaprol has a disagreeable skunklike odor and should be handled carefully to avoid spilling. Called also British antilewisite.


A chelating agent, developed as an antidote for lewisite and other arsenical poisons. It acts by competing for the metal with the essential -SH groups in the pyruvate oxidase system of the cells and forms, with arsenic, a stable, relatively nontoxic cyclic compound, the metal having a greater affinity for it than for the -SH groups of the cell proteins; also used as an antidote for antimony, bismuth, chromium, mercury, gold, and nickel.