NEW YORK (Reuters Health) - Duloxetine significantly reduces the frequency of stress incontinence episodes in a dose-dependent manner, even when the condition is fairly severe, according to a report in the American Journal of Obstetrics and Gynecology for July.

Duloxetine, a dual reuptake inhibitor of serotonin and norepinephrine, has been found to increase bladder capacity and the activity of the striated urethral sphincter in cats, Dr. Richard C. Bump, of Eli Lilly and Company in Indianapolis, and colleagues note. In a randomized phase II study, the investigators enrolled women who experienced at least four incontinent episodes per week for 3 months or more.

The intention-to-treat analysis included 132 women assigned to receive placebo, 132 to receive duloxetine 20 mg/day, 129 to receive duloxetine 40 mg/day, and 130 to receive duloxetine 80 mg/day.

After 12 weeks, the median reduction in incontinence episode frequency was 41% for placebo, 54% for duloxetine 20 mg/day, 59% for the 40 mg/day dose, and 64% for the 80 mg/day dose. The differences were significant for the two higher doses of the test drug. There were "virtually identical dose-dependent decreases" among those whose episode frequency was at least 14/week at baseline.

A 64% or greater reduction in incontinence episode frequency was experienced by half of the patients taking 80 mg/day, and two thirds had at least a 50% reduction in frequency of incontinence, with improvement seen within 4 weeks of starting drug treatment. In addition, subjects using duloxetine at any dose experienced significantly fewer voids per day and significantly increased time between voids.

Nausea was the most frequently reported adverse event. Five percent of subjects in the placebo group withdrew early, compared with 9%, 12% and 15% in the treatment groups at ascending dosages.

"This study provides evidence for the efficacy and safety of duloxetine in the treatment of stress urinary incontinence," Dr. Bump's team concludes. The group is now in the process of conducting large, multinational clinical trials.

Am J Obstet Gynecol 2002;187:40-48.

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