Polymer strip film is a promising dosage form for oral delivery of poorly water-soluble drugs. Drying is an important step in the production of polymer strip films with significant effects on critical quality attributes (CQAs). In this study, a custom-made batch drying setup was used to study convective drying kinetics of wet polymer strip films loaded with dry-coated micronized griseofulvin (GF) at various drying conditions. A rate-based semi-empirical model was formulated and parameters were estimated by integral method of analysis using a coupled optimizer-ordinary differential equation solver. Despite its simplicity with three parameters, the model could fit the experimental data very well for all drying conditions, which enabled us to examine the effects of air velocity, temperature, and initial wet film thickness on drying kinetics quantitatively. The modeling results clearly delineate a drying mechanism with constant-rate and falling-rate periods. One set of kinetic parameter estimates reasonably predicted the drying kinetics for two different wet film thicknesses in the selected process conditions, which demonstrates the predictive capability of the model. After reporting the limitations of the semi-empirical model, upon future modification and refinement, its potential use in drying process development and process control was highlighted.
Keywords: dry coating; drying kinetics; polymer strip film; poorly water-soluble drug.