Dr. Rebecca S. Nelken and colleagues note in the April 26 online issue of the journal Menopause that several studies have shown that vaginal estrogen improves symptoms of urinary urgency and frequency in postmenopausal women. They explain that the bladder and urethra have estrogen receptors, and it is believed that the thinning of the urothelium after menopause causes sensory urgency and more frequent urination, which is improved with local estrogen therapy.
This prompted the authors to perform a randomized trial of oxybutynin 5 mg BID or a vaginal ring releasing 7.5 mcg 17-beta estradiol daily (Estring; Pfizer) for the treatment of overactive bladder in 54 postmenopausal women.
After 12 weeks of treatment, both groups experienced a statistically significant and similar reduction in the mean number of daily voids, the researchers found. Specifically, the number decreased from 14.7 at baseline to 11.7 in the oxybutynin group, and from 14.9 to 10.4 in the estradiol ring group (p=0.71).
Quality-of-life scores also improved to a similar degree in both groups.
Significantly more women reported dry mouth in the oxybutynin group (85%) than in the vaginal ring group (22%), and corresponding rates of constipation were 52% vs 7%. On the other hand rates of vaginal discharge were 4% among women given oxybutynin compared with 41% of those receiving the estradiol ring.
After the trial, asked it they would like to continue with the same therapy, 85% of women given the vaginal ring said they would compared to 59% of women in the oxybutynin group.
Given these findings, Dr. Nelken and colleagues conclude, “The ultralow-dose estradiol-releasing vaginal ring might therefore be an effective and well-tolerated alternative to anticholinergic treatment of OAB (overactive bladder) in postmenopausal women.”
The study was supported by an unrestricted grant from Pfizer Inc., New York, NY.
Randomized trial of estradiol vaginal ring versus oral oxybutynin for the treatment of overactive bladder