A Strategic Shift from Batch to Continuous Flow for Modernizing Tianeptine Sustained-Release Tablet Process

Continuous manufacturing has emerged as a promising alternative to conventional batch processing in pharmaceutical production. However, transitioning established batch processes to continuous platforms remains challenging, particularly without altering formulations. Therefore, this study aims to evaluate the feasibility of converting a sustained-release (SR) dual-layer tianeptine sodium tablet from high-shear mixer granulation (HSM) to twin-screw granulation (TSG) while maintaining an identical formulation. A central composite design optimized key process parameters, and their effects on granule and tablet quality attributes were systematically assessed. Compared to HSM, TSG produced granules with broader particle size distributions and slightly reduced flowability; however, it produced tablets with higher hardness and lower friability. Both processes achieved the target dissolution profiles at early, intermediate, and late time points, and the similarity factor (f2 = 89.8) confirmed equivalence. Specifically, the TSG process reduced overall processing time by ~60%. These findings indicate that a quality-by-design-driven adjustment of process parameters enables successful batch-to-continuous conversion without formulation modification, supporting the strategic modernization of SR tablet manufacturing.