Male tolerance study of 1% C31G.

Background: C31G is being studied as a vaginal contraceptive and microbicide. This study was conducted to ensure that male partners of the women in future trials of C31G will not be subjected to an undue risk of penile irritation.

Methods: This was a randomized, double-blinded, single-center Phase I study in circumcised and uncircumcised men to assess penile irritation, safety and acceptability of seven consecutive daily doses of 1.0% C31G compared with a marketed spermicide, Extra Strength Gynol II(R) (3% nonoxynol-9) (ES Gynol II). Each participant was instructed to apply the study product to his penis at bedtime, to wash it off 6-10 h later, and to record any symptoms on a diary card. At the follow-up visit, a genital examination was performed and participants were again asked about adverse events and to complete an acceptability questionnaire.

Results: Of the 36 men enrolled, 12.5% of C31G users and 16.7% of Extra Strength Gynol II users reported product-related adverse events (AEs). All product-related AEs were considered mild by the investigator, except for one in the ES Gynol II group. Both products were acceptable.

Conclusion: The manner in which the products were used in this study is not the route by which men will be exposed to such products in actual use, and results should be considered in this light. Based on the observations in this study, C31G appears to be at least as safe and acceptable for male penile exposure as the marketed product ES Gynol II.