Antimicrobial in-situ forming gels based on bleached shellac and different solvents

Abstract

N-methyl pyrrolidone (NMP), dimethyl sulfoxide (DMSO), 2-pyrrolidone (PYR) and eutectic (1:1 menthol:camphor) were used as solvents for bleached shellac in doxycycline hyclate (DH)-loaded in situ forming gel. The apparent viscosity, rheology, syringeability, gel formation, degradability, drug release, and antimicrobial activity against Staphylococcus aureus, Streptococcus mutans and Porphyromonas gingivalis were investigated. DH loaded in-situ forming gels exhibited Newtonian or pseudoplastic flow and were able to be injected, and formed a gel after contact with simulated crevicular fluid. They inhibited S. aureus, S. mutans and P. gingivalis effectively. Fast diffusion of DMSO and NMP promoted the formation of a bleached shellac scaffold with an apparent burst DH release which initially occurred. DH-loaded in-situ forming gel containing bleached shellac using PYR as the solvent presented itself as the most appropriate preparation for periodontitis treatment because it sustained drug release and exhibited suitable degradation.