[Preparation and evaluation of Shedan in situ forming gel based on ocular characteristics]

To develop an ophthalmic preparation of Shedan, an in situ forming gel was prepared with the formulation containing 18% of poloxamer 407 and 5% of poloxamer 188 by response surface designs plus central composite designs. The rheology results showed that LVE range gamma should limited within 0.5%, Shedan high-frequency region, and the thixotropy recovery time is less than 5 seconds. The phase transition temperature was 33.25 °C according to curve of storage modulus and loss modulus determined by temperature scanning. Surface tension and osmometer of it determined by surface tension meter and dew point osmometer were 36.43 mN · m(-1), and 320.6 mOsm · kg(-1), respectively. Fluorescein sodium was selected as the marker to monitor the corneal residence time, and the results showed that Shedan gel could prolong drug residence for 180 min. In line with zero-order kinetics, releases of muscone and salvianolic acid B in vitro depends on gels erosion. The results of rabbit ocular irritation experiments suggested that Shedan in situ forming gel was biocompatible and nonirritant. In conclusion, a novel Shedan in situ forming gel was developed and characterized for potential drug treatment of retinal vein occlusion.