Surface Characterization as a Tool for Identifying the Factors Affecting the Dissolution Rate of Amorphous Solid Dispersion Tablets

An amorphous solid dispersion (ASD) is a commonly used approach to enhancing the dissolution of poorly aqueous soluble drugs. Selecting the desired polymer and drug loading can be time-consuming. Surface properties, such as surface composition and wetting behavior, are essential factors controlling the dissolution of ASD tablets. Thus, our study aims to use surface characterization to understand the factors that affect the dissolution rate of ASD tablets. In this work, we prepared ASDs with itraconazole and hypromellose acetate succinate (HPMCAS) using spray drying. ASDs were prepared using three grades of HPMCAS and different drug loading levels (10%, 30%, and 50%). We prepared ASD tablets with two porosities. For each tablet, contact angles were measured using the Drop Shape Analyzer; surface free energies, disperse, and polar fractions were calculated based on the contact angles. We conducted near-infrared (NIR) and dissolution measurements of ASD tablets. Principal component analysis (PCA) was carried out to investigate the NIR spectra further. The relative PCA scores were reported with other sample properties. A partial least square (PLS) model using NIR scores, tablets' wetting properties, and dissolution rates revealed that water and buffer contact angles, surface free energy, and polar fraction are the most significant factors attributing to the dissolution rate of ASD tablets. This work understood the interplay between the surface properties and the dissolution rate of ASD tablets. Moreover, surface characterization can be the tool to screen the formulation and compaction process of ASD tablets in early development.