FDM 3D printing has been recently attracted increasing research efforts towards the production of personalized solid oral formulations. However, commercially available FDM printers are extremely limited with regards to the materials that can be processed to few types of thermoplastic polymers, which often may not be pharmaceutically approved materials nor ideal for optimizing dosage form performance of poor soluble compounds. This study explored the use of polymer blends as a formulation strategy to overcome this processability issue and to provide adjustable drug release rates from the printed dispersions. Solid dispersions of felodipine, the model drug, were successfully fabricated using FDM 3D printing with polymer blends of PEG, PEO and Tween 80 with either Eudragit E PO or Soluplus. As PVA is one of most widely used polymers in FDM 3D printing, a PVA based solid dispersion was used as a benchmark to compare the polymer blend systems to in terms processability. The polymer blends exhibited excellent printability and were suitable for processing using a commercially available FDM 3D printer. With 10% drug loading, all characterization data indicated that the model drug was molecularly dispersed in the matrices.During in vitro dissolution testing, it was clear that the disintegration behavior of the formulations significantly influenced the rates of drug release. Eudragit EPO based blend dispersions showed bulk disintegration; whereas the Soluplus based blends showed the 'peeling' style disintegration of strip-by-strip. The results indicated that interplay of the miscibility between excipients in the blends, the solubility of the materials in the dissolution media and the degree of fusion between the printed strips during FDM process can be used to manipulate the drug release rate of the dispersions. This brings new insight into the design principles of controlled release formulations using FDM 3D printing.

PurposeThe filament-based feeding mechanism employed by the majority of fused deposition modelling (FDM) 3D printers dictates that the materials must have very specific mechanical characteristics. Without a suitable mechanical profile, the filament can cause blockages in the printer. The purpose of this study was to develop a method to screen the mechanical properties of pharmaceutically-relevant, hot-melt extruded filaments to predetermine their suitability for FDM.MethodsA texture analyzer was used to simulate the forces a filament is subjected to inside the printer. The texture analyzer produced a force-distance curve referred to as the flexibility profile. Principal Component Analysis and Correlation Analysis statistical methods were then used to compare the flexibility profiles of commercial filaments to in-house made filaments.ResultsPrincipal component analysis showed clearly separated clustering of filaments that suffer from mechanical defects versus filaments which are suitable for printing. Correlation scores likewise showed significantly greater values with feedable filaments than their mechanically deficient counterparts.ConclusionThe screening method developed in this study showed, with statistical significance and reproducibility, the ability to predetermine the feedability of extruded filaments into an FDM printer.Electronic supplementary materialThe online version of this article (10.1007/s11095-018-2432-3) contains supplementary material, which is available to authorized users.

Fused deposition modeling (FDM) three-dimensional (3D) printing is being increasingly explored as a direct manufacturing method to product pharmaceutical solid dosage forms. Despite its many advantages as a pharmaceutical formulation tool, it remains restricted to proof-of-concept formulations. The optimization of the printing process in order to achieve adequate precision and printing quality remains to be investigated. Demonstrating a thorough understanding of the process parameters of FDM and their impact on the quality of printed dosage forms is undoubtedly necessary should FDM advance from a proof-of-concept stage to an adapted pharmaceutical manufacturing tool. This article describes the findings of an investigation into a number of critical process parameters of FDM and their impact on quantifiable, pharmaceutically-relevant measures of quality. Polycaprolactone, one of the few polymers which is both suitable for FDM and is a GRAS (generally regarded as safe) material, was used to print internally-exposed grids, allowing examination of both their macroscopic and microstructural reproducibility of FDM. Of the measured quality parameters, dimensional authenticity of the grids was found to poorly match the target dimensions. Weights of the grids were found to significantly vary upon altering printing speed. Printing temperature showed little effect on weight. Weight uniformity per batch was found to lie within acceptable pharmaceutical quality limits. Furthermore, we report observing a microstructural distortion relating to printing temperature which we dub The First Layer Effect (FLE). Principal Component Analysis (PCA) was used to study factor interactions and revealed, among others, the existence of an interaction between weight/dosing accuracy and dimensional authenticity dictating a compromise between the two quality parameters. The Summed Standard Deviation (SSD) is proposed as a method to extract the optimum printing parameters given all the perceived quality parameters and the necessary compromises among them.