This invention discloses a bioadhesive boric acid formulation and its preparation method. Specifically, preferred vaginal bioadhesive boric acid formulation mainly comprises chitosan, carbopol 974 , polycarbophil, boric acid, and purified water as a gel. The main performance characteristic of this vaginal boric acid preparation is the ability of the formulation to retain and release boric acid in the vagina by using a combination of carbopol 974 and polycarbophil as preferred bioadhesive polymers. It was proved experimentally that boric acid as the antibacterial component of this gel can be maintained at a relatively high concentration (>10 mg/mL) in vagina for an extended period of time (>2 hours) with the use of a combination of polyacrylic acid polymers, i.e. carbopol 974 and polycarbophil. In order to prepare a gel of the said formulation with uniform continuity, boric acid was dissolved in water at the beginning of the process to make an aqueous solution and the bioadhesive polymers were added portion-wise into the aqueous solution with vigorous stirring. Further, it was demonstrated that the said vaginal bioadhesive boric acid formulation had a dynamic viscosity >100000 cps, pH value of 2 to 5, good moisture-retention capability. The formulation was non-allergenic, non-vaginal irritative, and capable of inhibiting bacteria and fungi.
