| Summary: | The transformation of a crystalline drug into an amorphous form is a promising way to enhance the oral bioavailability of poorly water-soluble drugs. Blending of a carrier, such as a hydrophilic polymer, with an amorphous drug is a widely used method to produce a solid dispersion and inhibit crystallization. This study investigates an experimental grade of hydroxypropyl methylcellulose acetate succinate, HPMCAS-MX (MX), as a solid dispersion carrier. Enhancement of thermal stability and reduction of the glass transition temperature (<i>Tg</i>) of MX compared with those of the conventional grade were evaluated through thermogravimetric analysis and differential scanning calorimetry (DSC). The formation of a homogeneous amorphous solid dispersion between MX and indomethacin was confirmed by X-ray powder diffraction analysis, DSC, and Raman mapping. It was observed that 10–30% MX did not act as an anti-plasticizer, but the utilization of >40% MX caused an increase in <i>Tg</i> and reduction of molecular mobility. This could be explained by a change in intermolecular interactions, inferred from infrared spectroscopy combined with principal component analysis. HPMCAS-MX exhibited similar performance to that of conventional-grade, HPMCAS-MG. Although HPMCAS-MX has thermal properties different from those of conventional-grade HPMCAS-MG, it retains its ability as a solid dispersion carrier.
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