Development and Evaluation of Minocycline Hydrochloride-Loaded In Situ Cubic Liquid Crystal for Intra-Periodontal Pocket Administration

In the present study, an injectable in situ liquid crystal formulation was developed for local delivery of minocycline hydrochloride (MH) for chronic periodontitis treatment. The physicochemical properties, phase structures, in vitro drug release and pharmacodynamics of in situ liquid crystals were investigated. The optimal formulation (phytantriol (PT)/propylene glycol (PG)/water, 63/27/10, w/w/w) loaded with 20 mg/g MH was proved to be injectable. The precursor formulation can form a cubic phase gel in excess water in 6.97 +/- 0.10 s. The results of in vitro drug release suggested the MH presented a sustained release for 4 days. Liquid crystal precursor formulation significantly reduced gingival index, probing depth and alveolar bone loss compared to the model group (p < 0.01). Besides, the pathological characteristics of model rats were improved. The results suggested that MH-loaded in situ cubic liquid crystal possessed of sustained release ability and periodontal clinical symptoms improvement. The developed in situ cubic liquid crystal may be a potentially carrier in the local delivery of MH for periodontal diseases.