Powder bed 3D-printing of highly loaded drug delivery devices with hydroxypropyl cellulose as solid binder.

3D-printing is a promising tool to pave the way to the widespread adaption of individualized medicine. Several printing techniques have been investigated and introduced to pharmaceutical research. Until now, only one 3D-printed medicine is approved on the US market. The medicine is manufactured via drop-on-powder deposition, which uses inkjet printing to jet a liquid binder on a powder bed to create 3D objects. However, inkjet processes are prone to nozzle clogging when binders or active pharmaceutical ingredients (APIs) are included in the printing ink. This renders the formulation development of the ink the most challenging step. In this study, different hydroxypropyl cellulose (HPC) grades were investigated as solid binders in the powder formulation on a commercially available DoP printer. The printed ink only consisted of a water/ethanol mixture. Formulations containing 70% caffeine as model API were developed and tablets printed. It was found that the friability of the tablets greatly depends on the particle size of the employed binder, whereas disintegration time and dissolution properties mainly depend on the viscosity of the employed binders. Higher viscous binders led to slower disintegration and dissolution whereas lower viscous binders led to faster disintegration and dissolution. The study demonstrates that HPC is a suitable solid binder for DoP printing and that 3D-DoP printing can be used to print robust dosage forms.