Refinement of PBK Models for Skin Absorption

This technical report discusses the refinement of physiologically-based kinetic (PBK) models specifically focusing on skin absorption using surrogate partition coefficient data. It outlines the importance of accurately assessing systemic exposure to topically applied personal care product ingredients, which relies on understanding the extent of ingredient absorption into the skin. The report details the methodology employed, including the use of the Transdermal Compartmental Absorption and Transit (TCAT) module from Simulations Plus Inc. The study involved measuring partition coefficients using polydimethylsiloxane (PDMS) to derive specific vehicle/water partition coefficients for various chemicals across multiple formulations. The results indicate that using these calculated coefficients generally improves PBK predictions for certain hydrophobic chemicals, while the method's effectiveness for hydrophilic items appears limited. The findings suggest a promising new approach for parameterization in PBK models, particularly for skin absorption studies involving hydrophobic substances.