Innovative Bioadhesive Buccal Films Containing Amlodipine Besylate: In Depth Characterization and Release Kinetics

This study focuses on the development of bilayer bioadhesive films containing amlodipine besylate for buccal administration. Films were prepared by solvent casting using bioadhesive polymers hydroxypropylmethylcellulose (HPMC), hydroxyethylcellulose (HEC), polyvinylpyrrolidone K30 (PVP K30) combined with a polycaprolactone (PCL) backing layer. Nine formulations (F1–F9) were evaluated for physicochemical and mechanical properties, including tensile strength, drug content, and in vitro release. ATR-FTIR and XRD analyses confirmed amorphous dispersion of the drug within the polymeric matrix, with no chemical incompatibility. The films exhibited uniform drug content (85–98%) and surface pH values ranging from 6.50 to 6.86, indicating good compatibility with the buccal mucosa. Mechanical testing showed tensile strength values between 16.40 ± 1.70 MPa and 177.64 ± 14.26 MPa, while the swelling index varied from 72.44 ± 3.16% to 295.10 ± 5.42%, depending on polymer composition. In vitro studies revealed prolonged release, with F3 achieving 83% cumulative release over 7 h. Kinetic modeling indicated that the Weibull model best described the data (adjusted R2 > 0.98), and Korsmeyer-Peppas suggested quasi-Fickian diffusion (n < 0.5). Formulation F3 was identified as optimal, exhibiting the highest swelling, superior tensile strength, and controlled drug release, making it suitable for prolonged buccal delivery of amlodipine besylate.