Most contraceptive vaginal gels are surfactant-based spermicides that contain the active ingredient nonoxynol-9, which kills sperm by destroying the cell membrane. Acidform gel (Amphora™), a new contraceptive vaginal gel, works by buffering the vaginal pH so that it maintains the vaginal environment at an acid pH despite the alkalinity of the incoming semen.METHODS:
A multicenter, randomized, open-label trial was conducted in 49 sites in the US and 13 sites in Russia to assess the 6-month pregnancy percentage of Acidform gel compared to nonoxynol-9. Participants were healthy, sexually active women between 18 and 45 years old. The primary outcome was pregnancy percentage over 6 months; secondary outcomes included acceptability and safety.RESULTS:
A total of 1,665 women were randomized to Acidform and 1,659 to nonoxynol-9. In the typical-use population (ages 18 to 35) the 6-month pregnancy percentages were 10.5% (95% CI 8.6–12.3) for Acidform and 10.0% (95% CI 8.1–11.9) for nonoxynol-9. With perfect use, the 6-month pregnancy percentage was 4.1% (95% CI 2.7–5.4) with Acidform. This was nearly identical to the 6-month percentage of 4.2% (95% CI 2.8–5.6) with nonoxynol-9. Fewer than 2% of subjects had adverse events that led to discontinuation. Significantly more Acidform users liked the method and would use it again (P less than .05 for both comparisons).CONCLUSION:
Acidform gel demonstrated 96% contraceptive efficacy at 6 months with perfect use. Both products studied were acceptable and few subjects had adverse events; however, more women using Acidform gel liked the method and would use it again.