Fesoterodine dose response in subjects with overactive bladder syndrome

To compare the efficacy of fesoterodine 4 mg versus 8 mg in treating subjects with overactive bladder (OAB) syndrome.

This is a pooled analysis of data from 2 randomized placebo (PBO)-controlled phase III trials. Eligible subjects with frequency and urgency or urgency urinary incontinence (UUI) were randomized to PBO or fesoterodine 4 or 8 mg for 12 weeks. Subjects assessed efficacy using 3-day bladder diaries recording the time of each void, urgency, and incontinence episode. Endpoints included treatment response (based on a 4-point Treatment Benefit scale) and change from baseline in micturitions, UUI episodes, mean volume voided, urgency episodes, and continent days. We assessed tolerability and safety by evaluating adverse events, residual urine volume, laboratory parameters, and treatment withdrawals.

At the end of treatment, both doses of fesoterodine showed statistically significant improvements in all efficacy endpoints versus PBO (P <0.01). These effects were seen 2 weeks after initiation of treatment (the earliest evaluation point) and were sustained throughout the treatment period. Fesoterodine 8 mg performed significantly better than fesoterodine 4 mg in improving all diary variables (P <0.05) except micturition frequency, demonstrating a dose-response relationship. Adverse events reported more frequently with fesoterodine than with PBO included dry mouth, constipation, and urinary tract infection.

Both fesoterodine 4 and 8 mg are effective in improving OAB symptoms. The higher 8-mg dose provides additional benefit compared with the lower dose in improving most bladder diary variables, thus offering the possibility of dose flexibility and titration.