A Phase 2, Randomized, Double-Blind, Efficacy and Safety Study of Oxybutynin Vaginal Ring for Alleviation of Overactive Bladder Symptoms in Women

PurposeWe evaluated the efficacy and safety of a once monthly oxybutynin vaginal ring in women with overactive bladder.Materials and MethodsThis randomized, multicenter, double-blind, 12-week phase 2 study compared oxybutynin vaginal ring (4 or 6 mg daily) to a placebo vaginal ring in women with well-defined overactive bladder symptoms. The primary efficacy variable was the change from baseline to week 12 in the total weekly number of incontinence episodes (stress and urge). Safety was measured in terms of treatment emergent adverse events, laboratory, physical, gynecologic examinations, electrocardiogram and vital signs.ResultsAfter a 3-week post-randomization placebo run-in phase (sample size 720) 445 women entered the treatment phase (safety population). Of these women 323 met all 3 overactive bladder specific baseline characteristics of 10 or more urinary urge incontinence episodes weekly, urinary frequency 8 or more voids per 24 hours and voided volume 3 L or less per 24 hours) (analysis population). Women treated with 4 and 6 mg daily oxybutynin vaginal ring had significantly fewer incontinence episodes weekly (p = 0.036 and p = 0.018, respectively), lower daily urinary frequency (p = 0.014, p = 0.002) and a higher proportion had no incontinence episodes at week 12 (p = 0.026, p = 0.027) compared with placebo. The change in severity of urgency and voided volume was similar for all groups (p >0.05). Except for a higher incidence of dry mouth and urinary tract infections that were not always culture confirmed, the oxybutynin vaginal ring was well tolerated and had a safety profile similar to that of the placebo vaginal ring.ConclusionsThe oxybutynin vaginal ring appears to be an effective and safe once monthly treatment option for women with overactive bladder characterized primarily by urinary urge incontinence that merits further evaluation in a phase 3 study.