Development of silicone-based barrier devices for controlled delivery of spermicidal agents

Abstract

Intravaginal devices (diaphragm and disc) were fabricated from silicone elastomer and evaluated for controlled release of Nonoxynol-9 (N-9). These intravaginal devices have good physical properties and reproducibility. A significant amount of N-9 was released within 2 min from vaginal devices; the release profile was found to follow Q vs. t 1/2 relationship. The release flux increased with increasing loading dose of N-9 from 10 to 40%, which followed a linear Q/t 1/2 vs. (2 A) 1/2 relationship, a typical characteristic of matrix-type drug delivery systems. The optimal loading dose of N-9 in diaphragms to achieve an appropriate release rate was of the order of 35%. The release flux of N-9 increased as the device shape changed from diaphragm to disc. Release flux of N-9 also increased with decreasing thickness of devices from 75 to 10 mil-inch. The release rate of N-9 from devices decreased as the duration of storage, after blending of N-9 into polymer parts before molding, increased. Spermicide-releasing disposable vaginal diaphragms containing N-9 were physically and chemically stable under various storage conditions for 16 weeks. Spermicide-releasing disposable vaginal diaphragms can offer a promising approach for achieving a controlled release rate of N-9 and consequent fertility control.