Can filaments be stored as a shelf-item for on-demand manufacturing of oral 3D printed tablets? An initial stability assessment

3D printing of oral solid dosage forms is a recently introduced approach for dose personalisation. Fused deposition modelling (FDM) is one of the promising and heavily researched 3D printing techniques in the pharmaceutical field. However, the successful application of this technique relies greatly on the mass manufacturing of physically and chemically stable filaments, that can be readily available as a shelf item to be 3D printed on-demand. In this work, the stability of methacrylate polymers (Eudragit EPO, RL, L100-55 and S100), hydroxypropyl cellulose (HPC SSL) and polyvinyl pyrrolidone (PVP)-based filaments over 6 months were investigated. Filaments manufactured by hot melt extrusion (HME) were stored at either 5 degrees C or 30 degrees C + 65 %RH with/without vacuuming. The effects of storage on their dimensions, visual appearance, thermal properties, and 'printability' were analysed. Theophylline content, as well as in vitro release from the 3D printed tablets were also investigated. The filaments were analysed before storage, then after 1, 3 and 6 months from the manufacturing date. Storing the filaments at these conditions had a significant effect on their physical properties, such as shape, dimensions, flexibility and hence compatibility with FDM 3D printing. In general, the methacrylate-based filaments were more physically stable and compatible with FDM 3D printing following storage. Owing to their hygroscopic nature, cellulose- and PVP-based filaments demonstrated a reduction in their glass transition temperature upon storage, leading to increased flexibility and incompatibility with FDM 3D printer. Theophylline contents was not significantly changed during the storage. This work provides preliminary data for the impact of polymer species on the long-term stability of filaments. In general, storage and packaging conditions have a major impact on the potential of on-demand manufacturing of 3D printed tablets using hot melt extruded filaments.

Automated summary

3D printing of oral solid dosage forms is a newly introduced approach for personalized dosing, with Fused Deposition Modelling (FDM) being a promising technique. The success of FDM relies heavily on the mass manufacturing of stable filaments. The study investigated the stability of various polymer filaments over 6 months and their impact on the potential of on-demand manufacturing of 3D printed tablets.