Release kinetics from oral thin films. Theory and experiments

In this work, a new millifluidic flow-through device is proposed for drug release studies from oral strips. The flow-through device mimics mouth physiological conditions thanks to the laminar tangential solvent flow, flow rates order of 1 mL/min and low hold-up volume (1 cm3). Drug release experiments have been performed on HPMC K15M thin films loaded with methyl orange with different initial drug loadings. A detailed analysis of data reproducibility and influence of flow-rates, film thickness and drug dosage on release curves is presented. A two-dimensional moving boundary model, describing drug transport in the swelling film and in the solvent flow channel is presented and solved numerically by FEM (Finite Elements Method). The theoretical model strongly supports the experimental observation that the time scales for complete drug release are significantly longer than expected when fluid dynamical conditions (close to mouth in-vivo conditions) are properly implemented in the experimental apparatus, and properly accounted for in the numerical modelling.