An injectable in situ hexagonal mesophase system for local delivery of minocycline hydrochloride: Preparation and pharmacodynamics in rats.

In this study, an optimized in situ reversed hexagonal mesophase loaded with minocycline hydrochloride (MH) was developed for the chronic periodontitis treatment. The in situ hexagonal liquid crystals (ISH2) comprised phytantriol (PT), propylene glycol (PG), water and vitamin E acetate (VitEA). The physicochemical properties, in vitro drug release and the therapeutic effects on chronic periodontitis of the formed samples were tested. The injectable liquid crystal-forming systems were characterized by crossed-polarized light microscopy, small angle X-ray scattering, and rheological measurements. The optimal ISH2 (PT/PG/water/VitEA, 56:27:10:7, w/w/w/w) loaded with 20 mg·g-1 MH was proved to be injectable with suitable pH, and was able to sustain the drug release for 10 days. The pharmacodynamic studies of the optimal formula were performed on male SPF rats, the Periocline® ointment was used as a control. The investigated ISH2 loaded with MH was demonstrated to be effective for periodontal treatment with significantly improved gingival index, pocket depth and alveolar bone loss. The developed ISH2 may be a promising application for local delivery system of MH in treating periodontal diseases.