Duloxetine compared with placebo for treating women with symptoms of overactive bladder

To evaluate duloxetine (a serotonin-noradrenaline reuptake inhibitor) in women with symptoms of overactive bladder (OAB), as it has been shown to increase the bladder capacity in an animal model.

In all, 306 women (aged 21-84 years) were recruited and randomly assigned to placebo (153) or duloxetine (80-mg/day for 4 weeks increased to 120-mg/day for 8 weeks; 153). Symptoms of OAB were defined as bothersome urinary urgency and/or urge urinary incontinence (UI) for > or =3 months. Participants were also required to have a mean daytime voiding interval (VI) of < or=2 h and urodynamic observations of either detrusor overactivity (DOA) or urgency which limited bladder capacity to <400 mL, both with no stress UI (SUI). The primary efficacy analysis compared the treatment effects on mean change from baseline to endpoint in the mean number of voiding episodes (VE)/24 h. The secondary efficacy analyses compared the treatment effects on the number of UI episodes (IE)/24 h, in the Incontinence Quality of Life questionnaire (I-QOL) score, and on the mean daytime VI. Safety was assessed with vital signs, adverse event reporting, routine laboratory testing, electrocardiogram, and the measurement of postvoid residual urine volumes (PVR).

Patients randomized to duloxetine had significant improvements over those randomized to placebo for decreases in VE and IE, for increases in the daytime VI, and for improvements in I-QOL scores at both doses of duloxetine. Urodynamic studies showed no significant increases in maximum cystometric capacity or in the volume threshold for DOA. The most common treatment-emergent adverse events with duloxetine (nausea, 31%; dry mouth, 16%; dizziness, 14%; constipation, 14%; insomnia, 13%; and fatigue, 11%) were the same as those reported by women with SUI and were significantly more common with duloxetine than placebo. Laboratory assessments, vital signs and electrocardiograms were stable relative to baseline, with no relevant differences detected between groups. There was a significant difference in the change in PVR with duloxetine (<5 mL mean increase) but no patient reported hesitancy or retention.

In this trial, duloxetine was better than placebo for treating women with 'wet' and 'dry' symptoms of OAB associated with DOA or a bladder capacity of <400 mL.