Modulation of Caffeine Permeation Kinetics in a Skin-PAMPA Model by Probiotic Lysates and Bile Acids

Background: Caffeine, although widely used in dermatological and cosmetic products, exhibits limited permeability through the stratum corneum, highlighting the need for strategies for optimizing delivery. The aim of this study was in vitro investigation of the effects of probiotic bacterial lysates and submicellar concentrations of bile acids on caffeine permeation, with a particular focus on permeation kinetics. Methods: Caffeine permeability was evaluated using the Skin Parallel Artificial Membrane Permeability Assay (Skin-PAMPA). Donor and acceptor concentrations were quantified by HPLC at predefined time points (1, 2, 4, 6, and 12 h), followed by calculation of apparent permeability coefficients, cumulative permeation profiles, and interval permeation rates in systems containing probiotic lysates and submicellar concentrations of cholic acid (CA) or deoxycholic acid (DCA). Results: Probiotic lysates significantly reduced caffeine permeability (0.98 ± 0.02 × 10^-6 vs. 1.57 ± 0.14 × 10^-6 cm/s in the control group) and modified transport kinetics resulting in lower early-phase interval permeation rates and reduced cumulative permeation. Conversely, bile acids increased the apparent permeability of caffeine, with the highest value observed in the DCA group (2.30 ± 0.08 × 10^-6 cm/s). Conclusions: Overall, probiotic lysates and bile acids modulated caffeine permeation across the Skin-PAMPA membrane primarily by reshaping permeation kinetics rather than simply changing overall permeability. Their combined effects may provide a basis for designing topical formulations with tailored permeation profiles.