Tailoring Immediate-Release Tablet Dissolution via Geometrically Tunable 3D-Printed Polymeric Coats

Background/Objectives: Conventional modification of drug release often requires reformulation of the drug-containing dosage form. This study investigated fused deposition modelling (FDM) 3D-printed polymeric coats as external barriers for modifying the dissolution of intact immediate-release tablets without reformulating the drug-containing core. Methods: Commercial tablets were encapsulated within 3D-printed polyvinyl alcohol (PVA) or polylactic acid (PLA) coats incorporating a continuous axial channel with surface apertures of 0, 4.5, or 9 mm diameter. Printing accuracy and dimensional fidelity were evaluated, followed by dissolution testing. Release profiles were characterized using zero-order, first-order, Higuchi, Weibull, and Korsmeyer–Peppas models. Results: Printed coats showed high dimensional fidelity. Fully enclosed PVA coats produced a prolonged lag phase followed by rapid release associated with coat hydration and loss of structural integrity, whereas fully enclosed PLA coats showed no detectable drug release over 6 h. Increasing aperture diameter increased release from both polymers, although the magnitude and pattern of release differed markedly between PVA and PLA. At 2 h, PVA coats with 4.5 and 9 mm apertures released 89.5 ± 10.4% and 97.0 ± 15.6%, respectively, compared with 1.90 ± 0.13% and 58.8 ± 9.5% from the corresponding PLA designs. Korsmeyer–Peppas analysis indicated apparent anomalous release for PVA 4.5 mm (n = 0.647) and PLA 9 mm (n = 0.711), while PVA 9 mm exhibited Super Case-II-like behavior (n = 1.214). Conclusions: FDM-printed external polymeric coats can substantially modify dissolution from intact immediate-release tablets. Release behavior depended on the interaction between aperture geometry and polymer properties, demonstrating the potential of external 3D-printed barriers as a flexible approach for tailoring drug-release profiles without reformulating the tablet core.