Comparison of Microbicides for Efficacy in Protecting Mice Against Vaginal Challenge With Herpes Simplex Virus Type 2, Cytotoxicity, Antibacterial Properties, and Sperm Immobilization

Abstract

Currently, a number of different over-the-counter spermicides and potential microbicides under development are in various phases of clinical trials. It is difficult to know how the various formulations would compare with each other or how efficacious they would be because no existing microbicides are commercially available. To evaluate, in a standardized manner, various parameters of potential microbicides. In an effort to make a comprehensive comparison, several potential microbicides and over-the-counter vaginal products were assayed for their efficacy in protecting mice from infection by herpes simplex virus type 2 (HSV-2), for their cytotoxicity to human vaginal epithelial cells, for their effect on the growth rate of L acidophilus, and for their spermicidal activity. Test formulations were K-Y Plus, Gynol II, Advantage S, Replens, BufferGel, No Fertil, Carrageenan, and PC-550. Additionally, several formulations were evaluated for their use as a possible placebo in microbicide clinical trials. The formulations tested fell into three categories of efficacy in protecting mice from HSV-2 infection. The most efficacious were Carraguard and PC-550. All the other test formulations except methyl cellulose afforded varying degrees of protection against herpes simplex virus-2 infection. It was found that formulations containing the surfactant N9 had a cytotoxic effect on human vaginal cells, inhibited the growth rate of L acidophilus, and exhibited spermicidal activity. In addition, it was found that Replens, BufferGel, No Fertil, and the Carbopol formulation might have some effect on sperm motility. Also, K-Y Jelly significantly inhibited the growth rate of L acidophilus. Evaluating formulations under the same testing conditions can help to distinguish among potential formulations that are likely to show promise as safe and effective microbicides.