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Succimer, sold under the brand name Chemet among others, is a medication tool used to treat lead, mercury, and arsenic poisoning. When radiolabeled with technetium-99m, it is used in many types of diagnostic testing.
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Common side effects include vomiting, diarrhea, rash, and low blood neutrophil levels.
Dimercaptosuccinic acid is in the chelating agent family of medications. It is on the World Health Organization's List of Essential Medicines. In the United States, no generic version was available as of 2015.
Medical uses
Succimer is indicated for the treatment of lead poisoning in children with blood level measured above 45 μg/dL. The use of dimercaptosuccinic acid is not approved for prevention of lead poisoning in anticipation of exposure in known lead-contaminated environments. Dimercaptosuccinic acid can cross the blood–brain barrier of mice, but it is not known if this is also the case in humans. Even if dimercaptosuccinic acid cannot reverse the damages done to the central nervous system, it might prevent further deterioration.
Succimer facilitates urinary excretion of lead, and with sufficiently aggressive treatment, can reduce lead content in the brain. It also increases urinary excretion of copper and zinc. Dimercaptosuccinic acid improved cognitive function in rats that had been exposed to lead, but reduced cognitive function in rats that had not been exposed to lead. or thioacetic acid followed by hydrolysis. The dimethyl ester is also known.
Meso 2,3-dimercaptosuccinic acid binds to "soft" heavy metals such as Hg<sup>2+</sup> and Pb<sup>2+</sup>, mobilizing these ions for excretion. It binds to metal cations through the thiol groups, which ionize upon complexation.
History
Dimercaptosuccinic acid was first synthesized by V. L. Nirenburg in the Urals Polytechnic Institute, commissioned by one of the electrical enterprises of Sverdlovsk, Russia, which consumed many tons of mercury and was looking for a medicine to prevent poisoning of personnel. In 1957, Chinese scientists found that dimercaptosuccinic acid can effectively treat antimony poisoning due to overdose of tartar emetic. Pronounced protective effect in animal poisoning with arsenic and mercury was first shown by I. E. Okonishnikova in 1962. In 1984, the now-defunct Bock Pharmaceutical Company requested the FDA grant approval for orphan drug status under the brand name Chemet and the FDA approved of this in 1991. It provided exclusivity until 1998 which was conveyed to the successor Sanofi in 1996.