Preparation and characterization of the ground mixture of rebamipide commercial tablets and Hydroxypropyl Cellulose-SSL by ball-milling: Application to the dispersoid of mouthwash suspension

In the present study, to prepare dispersoids with high dispersion stability that can be used as mouthwash, ground mixtures of commercial rebamipide (RB) tablets and hydroxypropyl cellulose (HPC-SSL) samples were prepared by dry milling. The physicochemical properties of the ground mixture of HPC-SSL and the powder obtained from the preliminary ground RB tablets were then compared. The dispersoids' physicochemical properties, dispersion stability, retention, and diffusiveness to the mucosal surfaces were evaluated in vitro. By co-grinding with HPC-SSL, RB transformed into fine particles around 303.6 - 361.5 nm that tended to prevent particle agglomeration in solution over time. The sample microparticles formed with HPC-SSL also avoided agglomeration on the mucosal surface for 24 h, improving oral retention. Furthermore, the ground mixture of HPC-SSL and the powder obtained from the preliminary ground RB tablets dispersed and permeated the mucus gel layer on the mucosal surface (24.2 %) but not the mucosal cells, indicating that RB remained on the mucosal surface. These results suggest that ground mixtures of commercial rebamipide (RB) tablets and hydroxypropyl cellulose (HPC-SSL) samples can be applied as a powdered suspension preparation because they showed high dispersion stability and oral mucosal retention.