Optimization and Evaluation of the Thermosensitive In Situ and Adhesive Gel for Rectal Delivery of Budesonide

Budesonide is a glucocorticoid for the treatment of ulcerative colitis (UC). The current study aims to develop a thermosensitive in situ and adhesive gel for rectal delivery of budesonide. HPMC K4M was selected as the adhesive agent based on the adhesive force and the effect on gel performance. The formulation of gel was optimized by using the central composite design-response surface methodology (CCD-RSM); a mathematical model was successfully developed to predict desired formulations as well as to analyze relationships between the amount of Pluronic F-127, Pluronic F-68, and HPMC K4M and the performances of gel. Based on CCD-RSM, a thermosensitive in situ and adhesive gel consisting of 0.002% budesonide, 0.74% HPMC, 4.87% F-68, and 19.0% F-127 was developed. Furthermore, the in vivo behavior of gel was evaluated in Sprague-Dawley rats. In comparison with budesonide solution, rectal administration of budesonide gel at 0.1 mg/kg in rats showed relative bioavailability of 230% with significant increase in rectum uptake.