Development and optimization of an in vitro release method for β-arbutin from chitosan-hyaluronic acid films

The aim of this study was to develop and optimize an in vitro method for evaluating β-arbutin release from chitosan-hyaluronic acid films for cosmetic use and to investigate the effects of hydrodynamic conditions and formulation composition on release behavior. Films containing β-arbutin were prepared by solvent casting with chitosan and hyaluronic acid as film-forming polymers. Glycerol, sodium citrate, and tannic acid were added as additives. Release studies were conducted in phosphate-buffered saline (PBS, pH 5.5) at 32 ± 0.5 °C and 50 rpm, using different medium volumes (50-200 mL) and two agitation systems. β-Arbutin concentration was determined by a validated UV-Vis spectrophotometric method. The method showed excellent linearity (R² = 0.9994), with LOD and LOQ values of 0.0035 and 0.0105 mg/mL, respectively. Hydrodynamic conditions affected release profiles, analytical applicability, and discriminatory ability of the method. Among the tested conditions, experiments in 100 mL of medium using a shaking water bath provided the most suitable balance between reliable quantification and discriminatory ability for preliminary formulation screening. All films showed rapid β-arbutin release, while formulation additives affected the early-stage release behavior. The developed method is a suitable tool for preliminary evaluation and comparison of cosmetic polymeric films containing β-arbutin.