|Jmol-3D images||Image 1|
|Molar mass||182.22 g/mol|
125 °C, 398 K, 257 °F
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Dimercaptosuccinic acid (DMSA), is the organosulfur compound with the formula HO2CCH(SH)CH(SH)CO2H. This colorless solid contains two carboxylic acid and two thiol groups, the latter being responsible for its mildly unpleasant odour. It occurs in two diastereomers, meso and the chiral dl forms. The meso isomer is used as a chelating agent.
DMSA was first synthesized by V. Nirenburg in the Urals Polytechnic Institute, commissioned by one of the electrical enterprises of Sverdlovsk, which consumed many tons of mercury and was looking for a medicine to prevent poisoning of personnel. In 1957, it was found by Chinese scientists that DMSA 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. Okonishnikova in 1962.
The 2,3-dimercaptosuccinic acid molecule has two stereocentres (two asymmetric carbons), and can exist as three different stereoisomers. The 2S,3S and 2R,3R isomers are a pair of enantiomers, whereas the 2R,3S isomer is a meso compound and thus optically inactive.
Preparation and reactivity 
Meso 2,3-dimercaptosuccinic acid binds to "soft" heavy metals such as Hg2+ and Pb2+, mobilizing these ions for excretion. It binds to metal cations through the thiol groups, which ionize upon complexation.
Medical use 
Dimercaptosuccinic acid (CHEMET) is indicated for the treatment of lead poisoning in children with blood level measured above 45 µg/dL. The use of DMSA is not approved for prophylactic/prevention of lead poisoning in anticipation of exposure in known lead contaminated environments. Its elimination half-life is 2.5-3.5 h. DMSA can cross the blood–brain barrier of mice, but not that of humans, limiting its use to extracting heavy metals from parts of the body other than the central nervous system.
Another application for DMSA is for provocation of tissue heavy metals in anticipation of a urine test. This is sometimes called a "challenge" or "provoked" heavy metals test. DMSA is used to help mobilize heavy metals stored in body tissues (and therefore not typically present in the circulation) and increase the excretion of heavy metals in the urine. In a study by Howard Frumkin et al., this sort of test was shown to not reliably provide an indication of past chronic mercury exposure, something it was often used for. A 2004 study by GP Archbold, et al. called the results of a DMSA challenge test "misleading" for the purposes of diagnosing mercury toxicity.
See also 
- Chelation therapy
- 2,3-Dimercapto-1-propanesulfonic acid
- Heavy metal poisoning
- Mercury poisoning
- Succinic acid
- Tartaric acid
- DMSA scan
- Merck Index, 11th Edition, 8854.
- Liang, Y., Chu. C, Tsen, Y., Ting, K. (1957). "Studies on antibilharzial drugs. Vl. The antidotal effects of sodium dimercaptosuccinate and BAL-glucoside against tartar emetic.". Acta Physiol. Sin. 21: 24–32.
- US 4550193, Lindemann, Martin K. O. & Lukenbach, Elvin R., "Process for the preparation of 2,3-dimercaptosuccinic acid and its lower alkyl esters", assigned to Johnson & Johnson Baby Products
- M. Gerecke, E. A. H. Friedheim, A. Brossi (1961). "Zur Kenntnis der 2,3-Dimercapto-bernsteinsäuren". Helvetica Chimica Acta 44 (4): 955–960. doi:10.1002/hlca.19610440410.
- Aasath, Jan; Dag Jacobsen, Ole Andersen, Elsa Wickstrøm (March 1995). "Treatment of Mercury and Lead Poisonings with Dimercaptosuccinic Acid (DMSA) and Sodium Dimercaptopropanesulfonate (DMPS)". Analyst 120: 853ff.
- Rooney, James (2007). "The role of thiols, dithiols, nutritional factors and interacting ligands in the toxicology of mercury". Toxicology 234 (3): 145–156. doi:10.1016/j.tox.2007.02.016. PMID 17408840.
- Guzzi, GianPaolo; Caterina A.M. La Porta (2008). "Molecular mechanisms triggered by mercury". Toxicology 244 (1): 1–12. doi:10.1016/j.tox.2007.11.002. PMID 18077077.
- Frumkin H, Manning CC, Williams PL, et al. (February 2001). "Diagnostic chelation challenge with DMSA: a biomarker of long-term mercury exposure?". Environ. Health Perspect. 109 (2): 167–71. doi:10.1289/ehp.01109167. PMC 1240638. PMID 11266328. Retrieved 2010-12-20.
- Archbold GP, McGuckin RM, Campbell NA (May 2004). "Dimercaptosuccinic acid loading test for assessing mercury burden in healthy individuals". Ann. Clin. Biochem. 41 (Pt 3): 233–6. doi:10.1258/000456304323019622. PMID 15117439. Retrieved 2010-12-20.
Further reading 
- Aposhian, H.V.; Aposhian, M.M. (1990). "Meso-2,3-dimercaptosuccinic acid: Chemical, pharmacological and toxicological properties of an orally effective metal chelating agent". Annual Review of Pharmacology and Toxicology 30 (1): 279–306. doi:10.1146/annurev.pa.30.040190.001431. PMID 2160791.