A randomized trial to determine the distribution of four topical gel formulations in the human vagina.

Background: There is an urgent need for the development of a topical microbicide to protect against sexually transmitted infections. We compared distribution and acceptability of four different gel formulations to be used as a vehicle for a microbicide.
Study Design: This is a randomized, double-blind comparative study. Six women tested each of the four gels at two different time points. Magnetic resonance imaging (MRI) scans were taken both within 10-15 min following intravaginal gel insertion and 4 h following gel insertion, before and after simulated intercourse at both time points.
Results: Vaginal surface contact immediately after insertion ranged from 68% to 92%. Simulated intercourse increased surface contact for all gels (range, 90-106%). After 4 h, surface contact ranged from 86% to 102%. Simulated intercourse at that time resulted in decreased coverage for two gels and increased coverage for two gels. One gel was noted to have consistent broad coverage of the vagina both immediately and 4 h after insertion, increased coverage with simulated intercourse at both time points and the lowest standard deviation of disruption at all time points.
Conclusion: MRI used in combination with qualitative assessments of acceptability can be used to select optimal gels for use as vehicles for potential spermicides or microbicides. We conclude that a gel consisting of 3% hydroxypropyl methylcellulose and 1.5% of methyl cellulose is the most promising candidate gel.