Effect of zinc oxide on the rheological and mucoadhesive properties of poloxamer 407-based mucoadhesive thermosensitive gel

Abstract

Background: To improve the therapeutic efficacy of drugs for hemorrhoid, mucoadhesive thermosensitive gel (MTG) system was developed. Methods: The MTG was prepared using poloxamer 407 (P407, 13% and 14%), polycarbophil (PC, 0.2% w/v), phenylephrine hydrochloride (0.25% w/v), lidocaine hydrochloride (1.88% w/v), and prednisolone acetate (0.05% w/v). Then, zinc oxide (ZnO) was added as an astringent as well as mucoadhesiveness-enhancing agent. Two kinds of poloxamer-based MTGs were compared in aspects of rheology, mucoadhesiveness, syringeability, and in vitro release study. Results: Both the two MTGs (13% and 14% P407) showed Newtonian behavior at 20 degrees C whereas pseudoplastic flow at 37 degrees C. The addition of ZnO into MTGs enhanced the mucoadhesiveness and syringeability and led the drug components to be released in accordance with Fickian mechanism. Conclusions: Taken together, the MTG-containing ZnO can be a more effective and convenient delivery system for the treatment of hemorrhoid with a reduced dosage interval.