| Nonoxynol(N-9) is one of the safest vaginal spermicides generally accepted and worldwidely used with many advantages, such as no serious side effects, free from formulation and medical nursing cares, offering emergent contraception and effective protection from sexually transmitted diseases. But most of the traditional vaginal spermicide delivery systems are of the characteristics of immediate release, high dosage, leakage and short effective period after administrating between 5 and 30 mins. The purpose of the present study was designed to develop two kinds of nonoxynol sustained release gels for pH and temperature sensibility, respectively, which would extend nonoxynol residence time in vagina, decrease adverse effects and be more convenient for patients to use.The preformulation results of bioadhesive polymers showed that polycarbophil(PCP), carbopol 974P(CP 974P) and xanthan gum had excellent bioadhesive properties compared with other polymers. PCP and CP 974P are pH sensitive, that is to say, their adhesion increases while pH ascends from 3 to 5, yet slightly decreases between 6 and 7. The combination of 18.2% Poloxamer 407 and 9% Poloxamer 188 produced the temperature sensibility, showing an outstanding adhesion gain under in situ condition compared with room temperature condition. The combination of PCP, CP and Poloxamer could further increase their adhesion.HPLC was utilized to determine the nonoxynol contents in gels, to assay the release and perfusion washing of nonoxynol sustained release gels.
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