Cholesterol in situ forming gel loaded with doxycycline hyclate for intra-periodontal pocket delivery.

Cholesterol has been widely used in drug delivery systems including implant. Doxycycline hyclate (DH)-loaded cholesterol in situ forming gels using N-methyl pyrrolidone as a solvent were prepared and investigated for their properties including viscosity, rheology, syringeability, gel formation, drug release, degradation and antimicrobial activities. The burst drug release of a DH-loaded in situ forming gel using cholesterol as the gelling agent was minimized when the amount of benzyl benzoate was increased. The viscosity of the system was increased as the amount of benzyl benzoate was increased with Newtonian flow. The systems were easy to inject into the target site because of their minimal force of syringeability. They could transform from solution into matrix-like structures, but formulations with higher concentrations of benzyl benzoate took a longer time. However, the degradability was decreased when the amount of benzyl benzoate was increased. These systems inhibited P. gingivalis, S. mutans and S. aureus effectively. DH-loaded cholesterol in situ forming gel system comprising 10% benzyl benzoate was the most suitable owing to its sustainable release manner for 10days and therefore was the proper formulation for periodontitis treatment.

Doxycycline hyclate-loaded bleached shellac in situ forming microparticle for intraperiodontal pocket local delivery.

Bleached shellac (BS) is a water-insoluble polyester resin made up of sesquiterpenoid acids esterified with hydroxy aliphatic acids. In this study, BS dissolved in N-methyl pyrrolidone (NMP), dimethyl sulfoxide (DMSO) and 2-pyrrolidone was used as the internal phase of oil in oil emulsion using olive oil emulsified with glyceryl monostearate (GMS) as the external phase of in situ forming microparticles (ISM). Doxycycline hyclate (DH)-loaded BS ISMs were tested for emulsion stability, viscosity, rheology, transformation into microparticles, syringeability, drug release, surface topography, in vitro degradation and antimicrobial activities against Staphylococcus aureus, Streptococcus mutans and Porphyromonas gingivalis. All emulsions exhibited pseudoplastic flow and notably low syringeability force. Slower transformation from emulsion into microparticles of ISM prepared with 2-pyrrolidone was owing to slower solvent exchange of this solvent which promoted less porous structure of obtained BS matrix microparticles. The system containing 2-pyrrolidone exhibited a higher degradability than that prepared with DMSO. Developed DH-loaded BS ISMs exhibited a sustainable drug release for 47days with Fickian diffusion and effectively inhibited P. gingivalis, S. mutans and S. aureus. Therefore a DH-loaded BS ISM using olive oil containing GMS as the external phase and 2-pyrrolidone as a solvent was a suitable formulation for periodontitis treatment.