Coprocessing of Pharmaceutical Cocrystals for High Quality and Enhanced Physicochemical Stability

Solid state synthesis of high-quality indomethacin–saccharin cocrystals was achieved using hot melt extrusion. The physical and chemical stability of the formed cocrystals was enhanced through coprocessing with inert excipients at the final kneading zone. For the purposes of the study, the synthesized cocrystals were coprocessed with a crystalline hydrophilic polymer (PEG 6000), an amorphous hydrophilic polymer (hydroxypropylmethyl cellulose, HPMC), and an aluminometasilicate inorganic (Neusilin) excipient. Physiochemical characterization of the suspended cocrystals in the Neusilin and HPMC carriers revealed superior stability and the absence of any interactions between the excipients and the parent cocrystals. In contrast extruded cocrystals that were not suspended in any excipient or coprocessed with PEG 6000 underwent disassociation under accelerated conditions. Surface dissolution analysis demonstrated that Neusilin and PEG 6000 have no effect on the cocrystal dissolution rates (>90%), while HPMC led to in situ gelling effect and hence in slower rates (∼4%). In conclusion, cocrystals with high crystallinity and improved physicochemical stability can be synthesized by coprocessing with excipients that are inert and nonmiscible and have good thermal stability and low viscosity