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International Journal of Bioprinting Semi-solid extrusion for pediatric medicine

Figure 4. Pictures of 3D-printed gummies. Adapted with permission from ref. Copyright © 2023 The Authors. Published by Elsevier B.V.
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Figure 5. Picture of 3D-printed suppositories. Adapted from ref. 85

2.2.4. Rheological properties within a few seconds after extrusion. 80,85,127,128 A thixotropic
The rheological properties of the material are central to the material is likely to have a viscosity that decreases as printing
successful execution of the SSE process and to obtaining progresses, causing the dosage form to collapse. Shear-
finished products of the desired quality. A notable thinning behavior ensures uniform extrusion with smooth
80
85
prerequisite for successful printing is that the raw material extrudates, preventing nozzle clogging. Conversely, if the
should ideally be shear-thinning 80,110,85,108,118 (i.e., the viscosity is too low, there is a risk of collapse of the dosage
viscosity of the material decreases as shear strain increases) form. 81,118 Therefore, it is necessary to formulate a semi-
and without thixotropy 80,85,127,128 (i.e., the viscosity of the solid raw material with appropriate viscosity, neither too
material should not decrease under constant stress over high to impede extrusion nor too low to prevent collapse.
time). The absence of thixotropy is important because the The viscosity of the material should allow extrusion only
viscosity of the material should not be time-dependent, and when pressure is applied and ensure a consistent extrusion
the successive layers should recover their initial structure rate so that the dosage form obtained meets specified

Volume 10 Issue 6 (2024) 51 doi: 10.36922/ijb.4063