Optimization of a Twin screw melt granulation process for fixed dose combination immediate release Tablets: Differential amorphization of one drug and crystalline continuance in the other.

Interest in Twin Screw Melt Granulation (TSMG) processes is rapidly increasing, along with the search for suitable excipients. This study aims to optimize the TSMG process for immediate-release tablets containing two different drugs. The hypothesis is that one poorly water-soluble drug requires amorphous conversion for improved dissolution, while the other water-soluble drug, with a higher melting point (T), remains more stable in its crystalline form. Ibuprofen (IBU) and Acetaminophen (APAP) were chosen as the model drug combination to test this hypothesis. Various diluents, binders, and disintegrating agents were assessed for their impact on processability, crystallinity, disintegration, and dissolution during development. The temperatures used during processing were below the T of all components, except for IBU. Melted IBU acted as a granulating aid in addition to the binders in the formulation, facilitating granule formation. Physicochemical analyses by Differential Scanning Calorimetry (DSC) and X-ray Diffraction (XRD) confirmed the complete conversion of IBU into an amorphous state and the preserved crystalline nature of APAP. Saturation solubility studies showed an improvement in IBU's solubility by ∼ 32-fold in 0.1 N HCl. Poor tablet disintegration performance led to the addition of disintegrating agents, where osmotic agents (sorbitol and NaCl) were found to significantly enhance disintegration compared to super disintegrants. The optimized formulation showed an enhanced IBU release (∼20 %) compared to the physical mixture (∼12.5) in 0.1 N HCl dissolution studies.