In Vitro Skin Absorption of the Topically Applied Metal Ion-Chelating Agent Diethylenetriaminepenta-acetic Acid

Diethylenetriaminepenta-acetic acid (DTPA) is a metal ion-chelating agent that has antimicrobial properties and potential therapeutic properties against metal-induced toxicities such as nickel allergy. In this study, the absorption properties of DTPA applied topically to rat skin are investigated in vitro, using a flow-through diffusion skin absorption model. [14C]DTPA was applied in solution in 60% ethanol (pH 6). Overall skin penetration into receptor fluid resulting from a topical dose of 0.13 mg/cm2 DTPA for 24 h was low at 1.27%. The local tissue distribution of DTPA was investigated using microautoradiography, and effects on the tissue were assessed by histology. Diethylenetriaminepenta-acetic acid was primarily associated with the stratum corneum and upper layers of the skin; minimal levels were observed in the dermis.