Long-term darifenacin treatment for overactive bladder in patients aged 65 years and older: analysis of results from a 2-year, open-label extension study

Objectives: This analysis evaluated the long-term safety, tolerability and efficacy of darifenacin, a muscarinic M-3 selective receptor antagonist, in the treatment of overactive bladder (OAB) in patients >= 65 years of age. Methods: Patients who completed one of two 12-week, placebo-controlled, double-blind, feeder studies received once-daily (o.d.) treatment with darifenacin 7.5 mg for the first 2 weeks of the 2-year, open-label extension study. The dose could be subsequently adjusted (7.5 or 15 mg o.d.) according to need. Safety and tolerability were assessed, and efficacy variables/endpoints were evaluated from patient diary data. Results: 214 patients (65-89 years) entered and 137 (64.0%) completed the 2-year extension study, amounting to 308 patient-years' drug exposure. Darifenacin was well tolerated with no new safety concerns. The most common adverse events (AEs) were dry mouth and constipation, which infrequently resulted in discontinuation (2.3% and 4.2%, respectively). Darifenacin produced significant improvements in OAB symptoms that were maintained over the 2-year period (median reduction from feeder-study baseline to 2 years: -11.0 [-83.7%] for incontinence episodes/week and -1.2 [-12.4%] for micturitions/day, both p < 0.05), with 44.4% patients achieving >= 90% reduction in incontinence episodes at 2 years. Conclusions: Darifenacin demonstrated good tolerability and safety in older patients with OAB. The improvement in OAB symptoms was sustained throughout the 2-year extension, resulting in high treatment persistence rates. Results were comparable with those in the overall OAB population from this study, indicating that darifenacin treatment is effective and well tolerated irrespective of age.