Meso-2, 3-dimercaptosuccinic acid (DMSA) is a sulfur-containing organic compound that is FDA approved for the treatment of lead and mercury toxicity both in children and adults. DMSA has been administered as a heavy metal chelator since the 1950s, and no other substance has been found to be more practical, safer, and more effective for this purpose.
It has long been recognized that sulfur-containing compounds have the ability to chelate heavy metals. Within the normal operation of the human body, there are natural sulfur-containing compounds which perform this service, and these include N-acetyl-Cysteine (NAC), R-Lipoic Acid, A-Lipoic acid, S-adenysl methionine (SAMe), and reduced glutathione (rGSH).
Meso-2, 3-dimercaptosuccinic acid (DMSA), does not occur naturally in the human body, nor is it a constituent of food. However, it has been studied for over 40 years as an effective oral chelator of heavy metals. Initial studies took place in the People’s Republic of China, Japan, and Russia and then spread to Europe and the USA.
Chemically, DMSA is a dithiol, which means that it contains two sulfhydryl (also know as S-H) groups, plus an analogue of Dimercaprol, also known as BAL, which is a lipid-soluble substance also used alone for metal chelation. However, unlike DMSA, BAL cannot be taken orally; rather it has to be injected deep into muscles in an oil solution. Moreover, BAL is much more toxic than DMSA. DMSA has a large therapeutic window, meaning that there is a wide margin between the amount needed to produce desired results and the amount that is potentially toxic. It can be said that DMSA is the least toxic of the dithiol compounds.
- DMSA mobilized lead mainly from soft tissue, especially blood, brain, kidney and liver. With respect to redistribution of mobilized lead to critical organs and magnitude of decline in soft tissue lead concentration, DMSA appears to be a safe and particularly effective Chelator and thus may be a viable alternative or choice in the presence of interindividual variability factor that may require the use of that to CaNa2EDTA.” (Cory-Slechta)
- “DMSA-chelated lead mainly reflects lead concentrations in blood, softtissue, especially blood, brain, kidney and liver. With respect to redistribution of mobilized lead to critical organs and magnitude of decline in soft tissue lead concentration, DMSA appears to be a safe and particularly effective Chelator and thus may be a viable alternative or choice in the presence of interindividual variability factor that may require the use of that to CaNa2EDTA.” (Cory-Slechta)
- “DMSA-chelated lead mainly reflects lead concentrations in blood, soft tissues, and possibly also trabecular bone.” (Gerhardsson)
- Urinary mercury excretion is significantly increased by DMSA administration. (Roels)
- DMSA acts as an antioxidant in vitro and lowers blood pressure in lab animals. (Khalil-Manesh)
- DMSA reverses (only) some of the lead-induced immunotoxicity” (Chen). However the use of an oral nutrient protocol given during the use of DMSA and post treatment protocol for the reactive oxidative stress has been developed to facilitate the recovery of the brain and organs from the chronic immunotoxic insult caused by long term heavy metal immunotoxicity.
- DMSA administration stimulates arsenic excretion in the urine. (Maehashi) When DMSA is taken orally, ABOUT 20% IS ABSORBED, blood level peaks in 2-4 hours. Excretion is much slower, with a half-life of approximately 2 days. (Facts & Comparisons) DMSA is primarily excreted in the urine, mostly as DMSA-cysteine disulfide. (Aposhian). Clinical experience indicated that a generally assumed absorption rate via rectal suppository, assuming an interindividual variability factor could be a conservative estimate of 75% absorption via the rectum. The peak blood levels should not differ appreciably.
- DMSA increases the excretion of ZINC AND COPPER. This requires an oral MV&M upon rising during the course of treatment.
- DMSA does not affect excretion of iron, calcium or magnesium.
(Facts & Comparisons) as does EDTA (without Na and Ca)
Challenge test for heavy metal intoxication
- “Two hour or four hour cumulative lead excretion after DMSA may provide an estimate of lead in storage sites that are most directly relevant to the health effects of lead. “ (Lee)
Heavy metal detoxification
- It is considered safe and effective in children at recommended doses.
- DMSA is labeled for use in children with blood lead concentrations in excess of 45 micrograms/dL. Evidence exists that DMSA is effective in lowering the blood lead concentrations in children with levels between 25 and 45 micrograms/dL.” (Berlin)
- DMSA is recommended as a single oral agent OR in combination with other chelating agents, however it is recommended that you gain experience with the use of DMSA as a single agent before proceeding the use of a combination therapy. DMSA has been shown to be effective for the detoxification of a number of heavy metals, including mercury, lead, cadmium and arsenic.
- DMSA seems to be promising in the treatment of occupational lead poisoning.” (Peru)
- Chelation therapy with DMSA in adults with moderate to severe lead poisoning is effective and safe. (Lifshitz)
- DMSA can be used in combination with EDTA chelation therapy in the treatment of severe lead intoxication in children; it is recommended that any combination therapy be monitored closely. (Gordon)
- DMSA offers encouragement with regard to its therapeutic potential for pregnant women exposed to methyl mercury. (Sanchez)
Additional Uses for DMSA
Dialkyltin compounds have been widely used in industry and agriculture, mainly as biocides, catalysts and plastic stabilizers. Toxic effects occur in the immune system, the bile duct, liver and pancreas. In a manner similar to organic arsenic, the toxicity of the dialkyltin compounds is related to reactions with biological dithiol groups. DMSA diminishes the production of bile duct, pancreas and liver lesions and inhibits the development of fibrosis of the pancreas and cirrhosis of the liver in lab animals exposed to these toxic chemicals. The decrease in the biliary excretion of these compounds by DMSA seems to be the reason for the pronounced protective effects of DMSA on bile duct, pancreas and liver. For these reasons DMSA has been recommended for the treatment of poisonings with dibutyltin compounds. (Merkord).