Transdermal oxybutynin in the treatment of adults with overactive bladder: combined results of two randomized clinical trials

The safety and efficacy of oxybutynin transdermal delivery system (oxybutynin-TDS) versus placebo in adults with urge and mixed urinary incontinence was investigated using combined results from double-blind stages of 2 phase3 clinical trials. Study 1: placebo-controlled, parallel-group comparison of 3 oxybutynin-TDS doses in 12-week double-blind and open-label periods, followed by a 28-week open-label extension. Study 2 was a 12-week randomized, double-blind, placebo-controlled comparison of oxybutynin-TDS versus long-acting tolterodine and placebo, followed by a 52-week open-label extension. Efficacy analysis included 241 patients receiving oxybutynin-TDS, 244 receiving placebo. Most participants were Caucasian women (92%). Approximately 60% received prior anticholinergic therapy. Primary outcome was determined by changes from baseline to end of treatment in frequency of incontinence episodes, frequency of urination, and void volume. Oxybutynin-TDS was significantly more effective than placebo in reducing median daily incontinence episodes (-3.0 vs placebo -2.0; P=.00004) and daily urinary frequency (-2.0 vs -1.0; P=.0023), and in increasing void volume (25 mL vs 5.5 mL; P <.00001). Overall rates of anticholinergic adverse events (AEs) were 12.8% for oxybutynin-TDS and 11.0% for placebo (P=0.5421). The most common systemic anticholinergic AEs were dry mouth (7.0% for oxybutynin-TDS vs 5.3% for placebo) and constipation (2.1% vs 2.0%). Application site erythema occurred in 7.0% of participants who received oxybutynin-TDS (3.7% discontinuation rate); pruritus occurred in 16.1% (3.3% discontinuation rate). Transdermal oxybutynin was shown to be efficacious, with a proven safety profile. It may be utilized for patients with overactive bladder as a treatment option that could enhance compliance.