Development of a hot-melt extrusion (HME) process to produce drug loaded Affinisol™ 15LV filaments for Fused Filament Fabrication (FFF) 3D printing

The aim of the present work was to develop a pilot scale process to produce drug-loaded filaments for 3D printing of oral solid dose forms by fused filament fabrication (FFF). Using hot melt extrusion, a viable operating space and understanding of processing limits were established using a hydrophilic polymer (hydroxypropyl methylcellulose (HPMC) - Affinisol™ LV15). This was then extended to formulate paracetamol (PCM) loaded Affinisol™ 15LV filaments across a wide range of compositions (5 - 50 wt% drug). From the process development work, challenges in achieving a pilot scale process for filament production for pharmaceutical applications have been highlighted. 3D printing trials across the range of compositions demonstrated limitations concerning the ability to print successfully across all compositions. Results from characterisation techniques including thermal and mechanical testing when applied to the formulated filaments indicated that these techniques are a useful predictive measure for assessing the ability to print a given formulation via filament methods. Oral solid dosage forms of variable surface area to mass ratios printed from suitable filament compositions demonstrated the ability to modify the release rates of drug for fixed formulations across substantial timescales.