Soaking-Loaded Diclofenac Sodium Buccal Films Fabricated by FDM 3D Printing

Intraoral drug delivery systems offer a promising alternative to conventional oral dosage forms by enabling direct systemic absorption and bypassing first-pass metabolism. In this study, diclofenac sodium (DS)-loaded intraoral films were fabricated using fused deposition modeling (FDM) 3D printing combined with a post-printing soaking-loading technique. The effects of soaking time, film pattern, and drug amount on drug loading capacity and in vitro membrane-controlled diffusion were systematically investigated. The physicochemical properties and content homogeneity of the films were evaluated, while drug-polymer compatibility was assessed using FTIR. In vitro membrane-controlled diffusion studies revealed controlled drug diffusion from all film formulations and demonstrated a significant influence of film pattern on release kinetics. After an 8-hour diffusion period, formulations F4 and F6 exhibited drug diffusion rates of 41.3% and 52.7%, respectively, whereas the DS solution showed a markedly higher diffusion rate of 78.1%. Films fabricated with a striped infill pattern displayed enhanced drug diffusion compared to flat-patterned films, which was attributed to increased surface area and the formation of microchannels within the polymer matrix that facilitated solvent penetration. Importantly, the soaking-loading approach enabled efficient drug incorporation without compromising the structural integrity of the printed films. To the best of our knowledge, this study is the first to demonstrate the combined effect of post-printing soaking-loading-based drug incorporation and film pattern design on drug diffusion behavior in FDM 3D-printed intraoral films. Overall, this strategy provides an innovative, non-invasive, and customizable platform for the development of personalized intraoral drug delivery systems.