Texture Analysis as a Printability Tool for Pharmaceutical FDM Filaments: A Review

Hot-Melt Extrusion (HME) coupled with Fused Deposition Modelling (FDM) 3D printing has emerged as a promising technology for developing pharmaceutical dosage forms, particularly patient-focused medicines tailored to individual needs. However, the successful processing of HME filaments by FDM remains challenging, as filament feedability and printability strongly depend on their mechanical properties. This review examines the mechanical characterization of HME-produced filaments, and its correlation with 3D printing performance, with a particular focus on texture analysis as a predictive tool for filament printability. Relevant literature on HME filament preparation, FDM processing, and mechanical characterization was scrutinized, with emphasis on texture analysis methods applied to polymeric filaments. The most common texture analysis methods, including three-point bending, buckling, stiffness and tensile tests, are comparatively discussed regarding their relevance to printability assessment, addressing both their methodological strengths and limitations. The review further summarizes the mechanical parameters associated with successful printing and discusses the influence of formulation and processing variables on filament performance, along with complementary properties including thermal, solid-state, rheological and morphological properties. By consolidating available evidence and identifying methodological gaps, this review provides a data-driven approach to filament formulation and process development, and positions texture analysis as a robust, informative and predictive strategy for evaluating filament suitability in pharmaceutical 3D printing.