EFFECT OF EXCIPIENT ON DRUG-RELEASE AND PERMEATION FROM SILICONE-BASED BARRIER DEVICES

Spermicide-releasing disposable vaginal devices were fabricated from s ilicone elastomer and evaluated for controlled release of Nonoxynol-9 (N-9). The optimal loading dose of N-9 in the diaphragm-shaped barrier device to achieve an appropriate release rate was of the order of 35% . Vaginal permeation of N-9 from disc-shape vaginal devices was neglig ible over the initial 5 h, and increased in a Q vs. t pattern. Several excipients were screened for spermicidal activity and for synergistic effects on the release rate of N-9 from diaphragm-shape barrier devic es. Incorporation of a cosolvent, Dow Coming silicone fluid (SF), into the vaginal devices facilitated burst release of N-9, and consequentl y reduced the required loading dose of N-9. Addition of 10% of SF in d iaphragms loaded with 25% of N-9 increased the release rate of N-9 to the equivalent of that from diaphragms loaded with 35% of N-9. SF incr eased the solubility of N-9 in silicone-based vaginal devices, but did not affect the permeation rate of N-9 through vaginal mucosa. Silicon e-based barrier devices can achieve a controllable release rate of N-9 within vagina, as well as a controllable permeation rate of N-9 throu gh vaginal mucosa, and therefore offer a promising approach for achiev ing fertility control.