A Pre-Phase III Efficacy Trial of the Spermicide/Contraceptive Effect of the Invisible Condom, a Non-Hormonal Vaginal Gel, in Women from Canada

Abstract

Objectives: To evaluate the spermicidal efficacy of non-hormonal vaginal gel in vitro and in a post-coital test, and to evaluate its contraceptive efficacy in Canadian women of childbearing age.

Methods: We conducted single-centre trial to assess spermicidal and contraceptive efficacy of vaginal gel. Participants were healthy, sexually active women aged 18-49 years and their regular male sexual partners (30 couples). Measured outcomes included effect of vaginal gel on sperm motility in vitro, its effect on sperm in a post-coital test, and its effect on pregnancy prevention over 3 months.

Results: For in vitro spermicidal effect, 98% and 67% of sperm were immotile in the presence of the gel with sodium lauryl sulfate (gel-SLS) and gel alone, respectively. For the post-coital test, 99% and 93% of sperm were immotile in the presence of gel-SLS and gel alone, respectively. In the second part of trial, a total of 410 instances of vaginal intercourse in 95 menstrual cycles were protected (during 3-month period of gel-SLS use before each sexual intercourse with probability of 24 conceptions prevented according to Wilcox's table). Four women became pregnant during the study period; 2 during unprotected vaginal intercourse around the time of ovulation, and 2 attributed to user failure.

Conclusion: Based on our results, the vaginal gel demonstrated important spermicidal and contraceptive effect. A larger phase III contraceptive efficacy trial is warranted. The vaginal gel may represent a non-hormonal spermicide/contraceptive option for women.

Keywords: administration, intravaginal; contraception, barrier; spermatocidal agents; women.