| Dimercaptosuccinic acid[1] | |
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meso-2,3-dimercaptosuccinic acid |
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Other names
succimer, APRD01236 (Drugbank), Chemet |
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| Identifiers | |
| CAS number | 304-55-2 |
| ChemSpider | 11285436 |
| UNII | DX1U2629QE |
| EC number | 259-952-2 |
| ChEMBL | CHEMBL1201073 |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | C4H6O4S2 |
| Molar mass | 182.22 g/mol |
| Melting point |
125 °C, 398 K, 257 °F |
| (verify) (what is: /?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
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.
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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.
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(meso-2,3-dimercaptosuccinic acid) |
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DMSA may be prepared by reacting maleic or fumaric acid with sodium thiosulfate followed by hydrolysis.[2] The dimethyl ester is also known.[3]
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.
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,[4] but not that of humans, limiting its use to extracting heavy metals from parts of the body other than the central nervous system.[5][6]
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.[7] A 2004 study by GP Archbold, et al. called the results of a DMSA challenge test "misleading" for the purposes of diagnosing mercury toxicity.[8]
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