Desired qualities and hypothetical contextual use of vaginal microbicides in a diverse sample of US women

Novel trichomonacidal spermicides

Metronidazole, the U.S. Food and Drug Administration-approved drug against trichomoniasis, is nonspermicidal and thus cannot offer pregnancy protection when used vaginally. Furthermore, increasing resistance of Trichomonas vaginalis to 5-nitro-imidazoles is a cause for serious concern. On the other hand, the vaginal spermicide nonoxynol-9 (N-9) does not protect against sexually transmitted diseases and HIV in clinical situations but may in fact increase their incidence due to its nonspecific, surfactant action. We therefore designed dually active, nonsurfactant molecules that were capable of killing Trichomonas vaginalis (both metronidazole-susceptible and -resistant strains) and irreversibly inactivating 100% human sperm at doses that were noncytotoxic to human cervical epithelial (HeLa) cells and vaginal microflora (lactobacilli) in vitro. Anaerobic energy metabolism, cell motility, and defense against reactive oxygen species, which are key to survival of both sperm and Trichomonas in the host after intravaginal inoculation, depend crucially on availability of free thiols. Consequently, molecules were designed with carbodithioic acid moiety as the major pharmacophore, and chemical variations were incorporated to provide high excess of reactive thiols for interacting with accessible thiols on sperm and Trichomonas. We report here the in vitro activities, structure-activity relationships, and safety profiles of these spermicidal antitrichomonas agents, the most promising of which was more effective than N-9 (the OTC spermicide) in inactivating human sperm and more efficacious than metronidazole in killing Trichomonas vaginalis (including metronidazole-resistant strain). It also significantly reduced the available free thiols on human sperm and inhibited the cytoadherence of Trichomonas on HeLa cells. Experimentally in vitro, the new compounds appeared to be safer than N-9 for vaginal use.

Effect of acculturation on the acceptability of potential microbicides and sexual risk-taking

BACKGROUND

The objective was to determine the acceptability and use patterns of potential microbicides among African American (AA), acculturated Hispanic (AH), and less acculturated Hispanic (LAH) women. We measured baseline sexual risk-taking and the likelihood of behavioral change, given effective microbicides.

METHODS

Interview of 506 Mexican-American and AA women, all of whom have a sexually transmitted infection enrolled in Project Sexual Awareness for Everyone.

RESULTS

The 3 groups reported similarly high acceptance of potential microbicides (76%-83% P = 0.24). LAHs were most likely to report they would use microbicides covertly (P = 0.03). Given the possibility of effective microbicides, AHs were consistently more likely to report risk disinhibition. AHs, as compared to LAHs and AAs, respectively, were most likely to report that they would not use condoms, (53% vs. 33% vs. 30% P <0.001), would have a 1-night stand (18% vs. 8% vs. 6% P = 0.02), or would have sex with humans before they got to know them (18% vs. 8% vs. 6% P = 0.01). AHs were also most likely to say they would or probably would change from baseline safe sexual practices to unsafe sexual behaviors if potential microbicides were available. Age was controlled for in the analysis as AHs were younger than AAs and LAHs.

CONCLUSIONS

Future microbicides were acceptable among this at risk cohort. Acculturation was a predictor of risk disinhibition and should be considered when tailoring sexually transmitted infection prevention messages, given the advent of effective microbicides.