Development of a Thermosensitive In-Situ Gel Formulations of Vancomycin Hydrochloride: Design, Preparation, In Vitro and In Vivo Evaluation

The purpose of this study was to develop a thermosensitive in situ gel delivery system based on Poloxamer 407 and Poloxamer 188 for ocular administration of vancomycin to treat systemic diseases. The vancomycin thermosensitive in situ gel was characterized using differential scanning calorimetry, rheological and drug release analyses. Additionally, pharmacokinetic studies and irritation tests of the gel were conducted after ocular administration in rabbits. The gel maintained a flowing liquid state under non-physiological conditions (25°C) to facilitate administration, and it transformed into a semi-solid state under physiological conditions (dilution with tears, 34°C), which prolonged its retention time in the eye. The gel erosion and drug release tests showed an excellent linear relationship between the cumulative drug release rate and the cumulative gel erosion rate, indicating a zero-order kinetic process. The pharmacokinetic analyses showed that the peak concentration, area under the curve, and bioavailability of the vancomycin thermosensitive in situ gel were 1.44, 1.98 and 1.93 times greater, respectively, that the values of vancomycin eye drops. Therefore, thermosensitive in situ gel may serve as a drug delivery system that can overcome the limitations of existing formulations of small-molecule peptides.