Release in vitro of dexamethasone sodium phosphate from thermosensitive in situ gels / 第三军医大学学报

ABSTRACT

Objective To investigate the release feature of dexamethasone sodium phosphate from thermosensitive in situ gels in vitro. Methods Rotation rheometer was used to measure the changes of viscosity with temperature. The membraneless model was applied in assessing corrosion behavior of gel using a thermostatic shaker (50 r/min) at an amplitude of 2.5 cm, taking phosphate buffered solution (pH 7.2) as releasing media. The release behavior was investigated by HPLC on a C18 reverse column DiamonsilTM (250 mm?4.6 mm, 5 ?m). The mobile phase consisted of triethylamine solution-methanol-acetonitrile (38∶28∶34), pumped at 1.0 ml/min, and the detection wavelength was set at 242 nm. Results When the temperature was near to the sol-gel transition temperature, the viscosity rose suddenly. Taking dexamethasone sodium phosphate (2 ml, pH 7.2) as media, the gel dissolution and drug release rate followed the zero order kinetics, and the cumulative gel dissolution (Q1) and cumulative drug release (Q2) equations were Q1=0.8238t (r=0.999, P