RESUMO
The ability of local mucoadhesive vaginal aqueous gel to deliver the antibacterial, antiprotozoal tinidazole [TND] to vaginal endolayers is dependent on its releasing out of the drug from vehicle to the mucosal layer of the vagina and then exert its local effect. This depends upon the physicochemical properties of the drug, vehicle and the composition of the releasing medium used. The effect of different concentration of carbomer 941[0.5, 1 and 2% w/w] on the release of TND [2%w/w] from the aqueous gel base in absence and presence of various concentration of propylene glycol [PG] to the stimulant vaginal fluid [S.V.F] medium was investigated. The release of TND from low concentration of carbomer [0.5% w/w] aqueous gel base was higher and its followed fickian mechanism of the release while an anomalous mechanism holds the releasing of drug from a high concentration of carbomer [1 and 2% w/w] aqueous gel base, the release of TND from aqueous gel containing low concentration of PG was markedly higher than that of aqueous gel having a higher concentration of PG. The solubility of TND in different concentration of PG: water solution were also investigated. The releasing method were carried out using both S.V.F [pH4.2] and citrate buffer [pH4.2]. It was found that the using of S.V.F considered to be useful for the evaluation of topically prepared vaginal dosage form as a releasing medium. Furthermore the swelling index or [swelling percent] of I gm carbomer polymer in S.V.F was measured after 4 hours incubation of the dry polymer in the fluid. The initial rate of swelling and the swelling equilibrium of [0.5, 1 and 2% w/w] dry carbomer in the S.V.F were also investigated, 0.5% w/w cabomer aqueous gel has a high rate of swelling and swelling to equilibrium size rapidly, while 1 and 2% w/w carbomer aqueous gel having a low rate of swelling and swelling to equilibrium size slowly