ASSESSMENT OF A TABLET DRUG-DELIVERY SYSTEM INCORPORATING NONOXYNOL-9COPRECIPITATED WITH POLYVINYLPYRROLIDONE IN PREVENTING THE ONSET OF PREGNANCY IN RABBITS

Objective: To assess the in vivo efficacy of the tablet drug delivery system containing nonoxynol-9 coprecipitated with polyvinylpyrrolidone by delivering the spermicidal agents vaginally and evaluating their a bility to prevent the onset of pregnancy in rabbits. Design: Controlle d clinical study. Setting: Division of Laboratory and Animal Resources , College of Pharmacy, University of Kentucky. Animal(s): Forty-two Ne w Zealand White female rabbits. Intervention(s): The rabbits were arti ficially inseminated at various intervals after vaginal insertion of t he tablet drug delivery system containing either polyvinylpyrrolidone only (0 minutes) or nonoxynol-9 coprecipitated with polyvinylpyrrolido ne (polyvinylpyrrolidone/nonoxynol-9; 0, 3, 30, 180, and 360 minutes). The rabbits were induced to ovulate 6 hours before insemination by IM injection of hCG (200 IU). Main Outcome Measure(s): The onset of preg nancy in the rabbits was evaluated after insertion of the tablet drug delivery system containing polyvinylpyrrolidone only or polyvinylpyrro lidone/nonoxynol-9 at various intervals, followed by artificial insemi nation. Result(s): The onset of pregnancy was not reduced significantl y when the tablet drug delivery system containing polyvinylpyrrolidone or polyvinylpyrrolidone/nonoxynol-9 was used and insemination was per formed immediately after tablet insertion (time 0). However, pregnancy rates (PRs) were reduced significantly in the rabbits that received t he tablet drug delivery system containing polyvinylpyrrolidone/nonoxyn ol-9 and were inseminated at 3, 30, 180, and 360 minutes after tablet insertion. The highest PR reduction occurred between 30 and 180 minute s after insertion of the tablet drug delivery system containing polyvi nylpyrrolidone/nonoxynol-9. Conclusion(s): The tablet drug delivery sy stem is an efficient method of delivering the tested spermicidal agent s vaginally. The design and dosage used in preparing the tablet drug d elivery system provide short-and long-term release of the spermicidal agents, which results in almost immediate and extended enhancement of their contraceptive properties. (C) 1998 by American Society for Repro ductive Medicine.).