Novel approach to evaluating granulation and segregation level considering the contribution of hydroxypropyl cellulose to the surface property change of granules.

The granulation process is critical to the uniformity of not only the active ingredient (API) but also other excipients in granules. Insufficient granulation results in unexpected product quality, e.g. delayed dissolution and lack of uniformity of API. Therefore, evaluating the granulation and segregation level of granules helps secure the uniformity of drug product quality. Here, we found that the polar surface free energy (SFE) of studied granules increased as granulation by a high shear granulator proceeded. Among the excipients formulated in the studied granules, only hydroxypropyl cellulose (HPC) showed a higher specific free energy of adsorption (ΔG) of chloroform, which is a parameter used to calculate polar SFE. This indicates that the ΔG of chloroform in granules helps detect the level of contribution of HPC to the granulation progress by inverse gas chromatography (IGC). We concluded that the ΔG of chloroform in a granulated sample is a novel critical material attribute (CMA) in relation to granulation level. In addition, we propose a novel approach to evaluating the quantitative granulation and segregation level based on the ΔG of chloroform in a granulated sample by focusing on the distribution of HPC in the granulated sample.