Single-Dose, Bioadhesive Clindamycin 2% Gel for Bacterial Vaginosis: A Randomized Controlled Trial

Objective: To assess efficacy and safety of a single-dose vaginal clindamycin gel for bacterial vaginosis treatment.

Methods: We conducted a double-blind, placebo-controlled, randomized study comparing clindamycin gel with placebo (2:1 ratio). Entry required clinical diagnosis of bacterial vaginosis, that is, all four Amsel's criteria, without other genital infections. Nugent scores of 7-10 were required for efficacy assessment, per updated 2019 U.S. Food and Drug Administration guidance. Patients were evaluated at screening, day 7-14, and day 21-30 (test of cure). Clinical cure was defined as resolution of three of four Amsel's criteria. Bacteriologic cure was defined as Nugent score lower than 4. Therapeutic cure was both clinical and bacteriologic cure. Primary outcome was clinical cure at the test-of-cure visit. Secondary endpoints were clinical cure at day 7-14, and bacteriologic and therapeutic cures at day 7-14 and test of cure. A sample size of 188 patients in the clindamycin group compared with 94 patients in the placebo group had 90% power to detect statistically significant difference (P=.05, 2-tailed).

Results: Participants were seen between July 9, 2020, and November 12, 2020. Of 307 randomized women, 56.0% were Black and 88.3% reported one or more previous bacterial vaginosis episodes. In the modified intention-to-treat population, 70.5% of patients in the clindamycin group and 35.6% in the placebo group achieved clinical cure at test of cure (primary outcome) (difference of 34.9, 95% CI 19.0-50.8), as did 77.5% of patients in the clindamycin group and 42.6% of patients in the placebo group in the per-protocol population (difference of 34.9, 95% CI 17.0-52.7). Statistically significant differences between groups were seen for all secondary endpoints. Clinical cure rate in patients in the clindamycin group with more than three bacterial vaginosis episodes in the prior year was 70.0%. Approximately 15% (15.3%) of patients in the clindamycin group experienced one or more treatment-emergent adverse events related to study treatment, as did 9.7% of patients in the placebo group. The most frequent treatment-related, treatment-emergent adverse event was vulvovaginal candidiasis.

Conclusion: A new, single-dose clindamycin vaginal gel was highly effective, with excellent safety, in women disproportionately affected by bacterial vaginosis, with Nugent scores of 7-10 at study entry.

Funding source: The study was funded by Daré Bioscience, Inc.

Clinical trials registration: ClinicalTrials.gov, NCT04370548.