Oscillatory shear rheology as an in-process control tool for 3D printing medicines production by fused deposition modeling

Abstract

Additive manufacturing has the potential to become a revolutionary tool in the production of improved pharmaceutical products. Nevertheless, the development of 3D medicines by fused deposition modeling (FDM) is still based on a trial-and-error method. Hence, this work designed a short and sensitive protocol based on oscillatory rheology and mechanical evaluation to assess hot-melt extrusion filaments viscoelastic behavior, define the ideal printing parameters, and predict their repercussions on the developed 3D tablets. For this purpose, polyvinyl alcohol filaments were produced using different plasticizer concentrations (glycerin) and subsequently printed on two different FDM 3D printers. The increase in plasticizer ratio (≥30%) enhanced viscous deformation, resulting in too flexible materials that are inappropriate for printing. On the other hand, filaments with 10–20% of plasticizer have adequate viscosity (close to 0.8 kPa·s), homogeneous diameter, and appropriate resistance to extensional force, resulting in suitable filaments to be pulled by the gear, flow through the nozzle, and build adequate 3D structures. Therefore, viscoelasticity and tensile strength measurements could anticipate problems in printability, possible printing errors, and instabilities of 3D medicines, which may ultimately increase drug product performance.