EDTA ethylenediaminetetraacetic acid is a widely used chelating agent in chelation therapy for treating heavy metal poisoning, including lead poisoning. The coordination chemistry of EDTA involves the formation of stable complexes with metal ions through the donation of electron pairs from its multiple functional groups.EDTA is a hexadentate ligand, which means it can form six coordinate bonds with a central metal ion. Its structure contains two nitrogen atoms from the ethylenediamine group and four oxygen atoms from the carboxylate groups. These atoms serve as electron pair donors, allowing EDTA to form strong coordinate covalent bonds with metal ions.In the case of lead poisoning, EDTA binds to lead ions Pb2+ through its six donor atoms, forming a stable and soluble complex called Pb EDTA 2-. This complexation process involves the replacement of water molecules or other ligands that were initially coordinated to the lead ion. The formation of the Pb EDTA 2- complex effectively reduces the concentration of free lead ions in the body, which are responsible for the toxic effects of lead poisoning.The mechanism of action of EDTA in lead poisoning treatment can be summarized as follows:1. Administration of EDTA: EDTA is typically administered intravenously or intramuscularly to ensure rapid distribution throughout the body.2. Complexation with lead ions: EDTA forms a stable and soluble complex with lead ions Pb2+ by donating electron pairs from its six donor atoms two nitrogen and four oxygen atoms .3. Reduction of free lead ion concentration: The formation of the Pb EDTA 2- complex reduces the concentration of free lead ions in the body, thereby decreasing their toxic effects.4. Elimination of lead-EDTA complex: The Pb EDTA 2- complex is water-soluble and can be readily excreted by the kidneys through urine, effectively removing lead from the body.It is important to note that EDTA is not selective for lead ions and can also form complexes with other metal ions, such as calcium, magnesium, and zinc. Therefore, chelation therapy with EDTA should be carefully monitored to avoid potential side effects related to the depletion of essential metal ions.