ABSTRACT:
This article presents the results of the development and experimental validation of a film-coating technology for modified-release tablets, and examines the scalability of this process from laboratory to industrial scale. The model system used was 133 mg tablet cores coated with a suspension composition based on a methacrylic acid-ethyl acrylate copolymer (1:1) with a 90% aqueous phase content. Experimental studies were conducted on ASC-5F (5 L) and LDB-150 (50 L) units using single- and four-nozzle spray systems. It was shown that the critical process parameters determining dissolution kinetics and coating quality are the drying air temperature and spray rate. Optimum ranges are: inlet air temperature of 51-58°C, outlet air temperature of 41-45°C, and spray rate of 1.5-3.5g/min. To ensure accurate scaling, calculation approaches based on the Froude number, specific suspension flow rate, and air-to-liquid flow ratio were proposed. Since the impact of the nozzle airflow on the tablet layer and the potential "swelling" of individual cores are critical factors affecting coating uniformity, it was decided not to change these parameters between experiments. Maintaining constant spray and air flow conditions minimized the risk of layer destabilization and ensured comparability of the results. The study results allowed the coating process to be adapted from 5-liter laboratory equipment to 50-liter industrial equipment while maintaining dynamic similarity and reproducibility of process parameters. The developed approaches can be used in the design, validation, and technological support of film coating processes in pharmaceutical manufacturing.