Process optimization of personalized theophylline printlets via direct extrusion AM

In recent years, the application of additive manufacturing processes in pharmaceutical production has been increasingly investigated, with the aim of manufacturing personalized tablets tailored to the medical needs of individual patients. This technology enables the fabrication of dosage forms with high variability in both dose and geometry, while maintaining relatively low production costs. Among the investigated technologies, Direct Extrusion Additive Manufacturing (DEAM) represents a promising approach, as it allows the processing of raw materials such as pellets, granules, and powders, overcoming the limitations associated with fused filament-based technologies (FFF). In this study, the use of DEAM for the production of pharmaceutical tablets from powder and granule mixtures is investigated. The pharmaceutical formulations are based on theophylline as the active pharmaceutical ingredient (API), combined with Kollidon® and Soluplus® as polymeric matrices, together with suitable excipients to improve printability. A modified Prusa i3 MK3 3D printer equipped with a screw-assisted extrusion unit was employed to process the formulations. The work focuses on process optimization through the adjustment of the main printing parameters, with the objective of identifying operating conditions that allow stable extrusion and satisfactory printing quality. In addition, a thermographic analysis was performed to evaluate the thermal distribution along the extrusion unit and to investigate its influence on the extruded flow behavior. The printed tablets were subsequently evaluated in terms of quality in order to validate the selected processing conditions.