The role of amino acids supplementation of protective Na2H2EDTA containing ointments in chelation of allergenic metal ions.

The chelating agents are often used as an active ingredients in the protective ointments because of their capacity of allergenic metal ions binding and reducing its penetration through the skin. The most effective ligands yet discovered preventing from metal ions induced dermatitis include ethylenodiaminetetraacetic acid (EDTA), diphenylglyoxime and dimethyloglyoxime and clioquinol (1). EDTA can be used in topical barrier creams as monoto tetra-substituted salts or in the chelating complexes such as cyclohexane-1,2-diaminetetraacetic acid (CDTA) or diethylenetriaminepentaacetic acid (DTPA) (2, 3). Little is known about the influence of the additional chelating molecules introduced into the protective ointment containing with the primary chelating ligand on the efficacy of allergenic metal ions binding (4). The aim of the study was to evaluate the effect of presence of selected amino acid ingredient on the chelation ability of Ni or Co ions of the protective ointment containing 10% disodium salt ethylenodiaminetetraactic acid (Na2H2EDTA∑2H2O). Three amino acids (glycine ñ Gly, aspartic acid ñ Asp and histidine ñ His) in two concentrations and two pharmaceutical formulations were tested in the diffusion glass chamber with artificial membrane.