Tailoring amlodipine release from 3D printed tablets: Influence of infill patterns and wall thickness

The aim of this study was to investigate the impact of infill patterns on the drug release of 3D-printed tablets and the possibility of tailoring drug release through the use of excipients. Furthermore, the influence of wall thickness was evaluated. Amlodipine was used as a model drug, polyvinyl alcohol (PVA) as a polymer and excipients including sodium starch glycolate (SSG) and hydroxypropyl methyl cellulose (HPMC) HME 4 M were used. Four different formulations were prepared. Firstly, the substances were mixed and then extruded by hot melt extrusion to form filaments. The obtained filaments were used to print amlodipine tablets by fused deposition modeling (FDM) 3D-printing technique. Each formulation was printed in four different infill patterns: zigzag, cubic, trihexagon and concentric, while infill density remained constant (20%). The mechanical properties of the obtained filaments were also evaluated using three-point bend test. Amlodipine tablets were printed with varying wall thickness (1 mm, 2 mm and 3 mm) and varying infill patterns. With regard to the infill patterns, higher drug release was achieved with zigzag infill pattern. The simultaneous effect of excipients and infill patterns on amlodipine release has been described and modeled through self - organizing maps (SOMs), which visualize the effect of these variables. Self-organizing maps confirmed the fastest drug release when the zigzag pattern and SSG were used, but also showed that the presence of HPMC HME 4 M was not decisive for drug release rate. As for the wall thickness, higher drug release was achieved with decreasing wall thickness. The results indicated that proper selection of excipients and/or adjusting the infill pattern and wall thickness are ways of tailoring drug release in FDM 3D printing. This study draws the attention to the importance of adjusting the settings of the printer and the usage of excipients to produce release-tailored medications