Succimer is excreted predominantly in the urine, where 80%–90% appears as mixed disulﬁdes. Peak blood concentrations are reached in approximately 3 h. After absorption, greater than 90% of succimer in the blood is found in the plasma fraction, where it is highly bound (92%–95%) to plasma proteins (mainly albumin) by disulﬁde linkages. It forms water soluble chelates with heavy metals which are subsequently excreted renally.Ħ Chemical Properties Succimer (C4H6O4S2 molecular weight g/ mol) is a white crystalline powder that is soluble in aqueous alkaline solutions, such as 5% sodium bicarbonate.ħ Pharmacodynamics In addition to increasing excretion of toxic metals, such as lead, mercury, and arsenic, in human and animal studies, succimer has been associated with increases in the urinary excretion of zinc and copper in human trials.Ĩ Pharmacokinetics Approximately 20% of orally administered succimer is recovered in the urine as the parent compound or metabolites in human studies. Oral DMSA was approved by the US Food and Drug Administration in 1991 as an orphan drug for the treatment of childhood lead poisoning.

Borderline metals, such as Pb2+, Cd2+, Cu2+, As3+, and Zn2+, prefer nitrogen-donating ligands, but will also react with both hard and soft ligandsĥ Succimer Succimer is the generic name for meso-2,3dimercaptosuccinic acid (DMSA). Hard metals, such as Na+, K+, Mg2+, Ca2+, and Al3+, are referred to as oxygen seekers and form the best complexes with hard ligands containing a carboxyl (COO–) group such as calcium disodium edetate (CaNa2EDTA).

BAL has two adjacent sulfur groups, thus the term dithiol. The chelator or ligand, in this case a sulfur-containing compound such as dimercaprol (BAL), forms a coordinate bond with the metal by donating a pair of free electrons.

Accordingly, they form the most stable complexes with sulfur donors and are therefore referred to as sulfur seekers. Soft metals such as Hg2+, Au+, Cu+, and Ag+ have large atomic radii with a large number of electrons in their outer shell. Succimer Calcium disodium Edetate Dimercaprol D-pencillamine Dr Rokhsareh Meamar MD, Ph.D Associate Professor of Medical Sciences Department of Medical Toxicology, Isfahan University of Medical sciencesĢ Chelation therapy The indications for and speciﬁcs of chelation therapy are determined by patient age, blood-lead concentration, and clinical symptomatology.

Lead poisoning antidote