From Digital Design to Dosage Performance: Material-Process-Geometry Interactions in 3D-Printed Oral Tablets

Additive manufacturing (AM) allows for digital control of the geometry, internal design, and dosage of oral solid dosage forms, thus broadening the horizon of applications. However, the release of drugs from 3D-printed tablets is often explained in terms of geometry alone, without adequate attention to material properties and processing conditions. This review argues that release behavior is the result of material-geometry-process interactions, rather than geometry alone. A critical analysis of the recent literature (2019-2025) on various methods such as fused deposition modeling (FDM), selective laser sintering (SLS), stereolithography/digital light processing (SLA/DLP), semi-solid extrusion (SSE), powder-bed deposition, and inkjet printing reveals the contexts in which geometry can be controlled. Generally, geometry affects release only within material-process stability windows, which are determined by the rheology of polymers, thermal processing, powder sintering, photopolymer crosslink density, or droplet transport. In these contexts, geometry is a secondary control parameter after material state optimization and process development. This review combines the paradigms of Quality by Design (QbD) and Process Analytical Technology (PAT), focusing on real-time monitoring of key process variables and microstructural critical quality attributes to control geometry. The results have implications for regulatory and translational issues, such as inter-printer variability, feedstock qualification, and the absence of geometry-specific bioequivalence guidelines. By viewing geometry-controlled release as an effect of material-geometry-process interactions, this review offers a mechanistic and quality-focused rationale for technology choice, formulation development, and regulatory compliance in pharmaceutical additive manufacturing.