Screening pharmaceutical excipient powders for use in commercial 3D binder jetting printers

Binder jetting is an additive manufacturing technique that creates three-dimensional constructs from a powder feedstock. It is used by several industries, including pharmaceuticals. This additive approach to manufacture provides several functional benefits that are not easily achievable using conventional manufacturing methods. There is currently only limited publicly available knowledge that details the requirements of an effective binder jetting powder. Specifically in the pharmaceutical industry, since the 2015 release of Spritam (R), a binder-jetted tablet containing levetiracetam, no new pharmaceutical tablets have been produced using such methods. There appears to be gap in powder technology expertise and the development of 3D printing processes. Our goal is to enhance our knowledge in terms of powder flow, powder wetting and powder binding to link particles with process and build the capability to create a greater range of powders suitable to be binder-jetted into new products. After initially screening several standard pharmaceutical excipient powders for their relevant properties, two candidates showed best fit potential for use in binder jetting, specifically microcrystalline cellulose (Pharmacel 101 and 102) and lactose (Lactohale 200). Using simple formulations of these pharmaceutical excipient powders as a model, we analysed for printability and powder performance using a range of quantitative parameters including dimensional accuracy, construct hardness, friability, porosity and surface finish. In general, formulations of these powders showed good printability, but some powder blends produced constructs with more obvious manufacturing imperfections. Several routes to improve the printability of these pharmaceutical powders are proposed for future works. Ultimately, this work provides a fundamental basis to start to quantitatively assess the potential of standard pharmaceutical excipient powders in binder jetting printers using powder characterisation techniques and print quality outcomes. (C) 2021 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.