Duloxetine: a new approach for treating stress urinary incontinence

Duloxetine is a potent and balanced dual serotonin and norepinephrine reuptake inhibitor (SNRI) that enhances urethral rhabdosphincter activity and bladder capacity in a cat irritated bladder model. Whether this is beneficial in women suffering from stress urinary incontinence (SUI) has been investigated in one phase 2 and three phase 3 placebo-controlled clinical trials with very comparable inclusion and exclusion criteria and outcome variables. In addition, one phase 3 study was performed in women with SUI awaiting incontinence surgery. These trials involved investigational centers in 5 continents: North America, Europe, Australia, South America and Africa. Duloxetine 80 mg per day (40 mg twice daily) decreased the frequency of incontinence episode frequency (IEF) and improved incontinence-related quality of life (I-QOL) independent of baseline incontinence severity and also in patients awaiting surgery. In the trial in patients awaiting surgery, onset of action was closely monitored and all patients who responded to duloxetine did so within 1-2 weeks. The decrease in IEF and improvement in I-QOL were not due to more frequent voiding, as the mean time between voids increased. Nausea was the most common treatment emergent adverse event. This was mostly experienced early after the start of duloxetine (usually within the first few days) and was usually mild or moderate and non-progressive in severity. The majority of patients reporting nausea continued treatment with duloxetine and in most of these patients the nausea resolved within 1 to 4 weeks. It can, therefore, be concluded that duloxetine 40 mg twice daily is a new and promising pharmacological treatment approach for women with SUI.