Evaluating Swellable Cross-Linked Biopolymer Impact on Ink Rheology and Mechanical Properties of Drug-Contained 3D-Printed Thin Film

Interest in 3D printing oral thin films (OTFs) has increased substantially. The challenge of 3D printing is film printability, which is strongly affected by the rheological properties of the ink and having suitable mechanical properties. This research assesses the suitability of sodium starch glycolate (SSG), a swellable cross-linked biopolymer, on ink rheology and the film's mechanical properties. A water-based ink comprising sodium alginate (SA), the drug fenofibrate (FNB), SSG, glycerin, and polyvinylpyrrolidone (PVP) was formulated, and its rheology was assessed through flow, amplitude sweeps, and thixotropy tests. Films (10 mm × 15 mm × 0.35 mm) were 3D-printed using a 410 µm nozzle, 50% infill density, 60 kPa pressure, and 10 mm/s speed, with mechanical properties (Young's modulus, tensile strength, and elongation at break) analyzed using a TA-XT Plus C texture analyzer. The rheology showed SSG-based ink has suitable properties (shear-thinning behavior, high viscosity, higher modulus, and quick recovery) for 3D printing. SSG enhanced the rheology (viscosity and modulus) of ink but not the mechanical properties of film. XRD and DSC confirmed preserved FNB crystallinity without polymorphic changes. SEM images showed surface morphology and particle distribution across the film. The film demonstrated a drug loading of 44.28% (RSD 5.62%) and a dissolution rate of ~77% within 30 min. SSG improves ink rheology, makes it compatible with 3D printing, and enhances drug dissolution (formulation F-5). Plasticizer glycerin is essential with SSG to achieve the film's required mechanical properties. The study confirms SSG's suitability for 3D printing of OTFs.