This study will evaluate safety, efficacy and patient's perception of outcome after treatment with darifenacin (7.5 mg once daily (o.d.) with voluntary increase up to 15 mg o.d.) in patients with OAB who are dissatisfied with prior oxybutynin extended release (ER) or tolterodine extended release (ER) therapy.

Inclusion Criteria:

• • Symptoms of OAB for at least six months prior to randomization

  • ≥ 8 micturitions on average/24 hours

  • ≥ 1 urgency episodes on average/24 hours

  • with or without UUIE

    • Patients dissatisfied with prior oxybutynin ER or tolterodine ER treatment. Patients must have been on either treatment for at least 1 week and up to 12 months preceding this study. It is required that either oxybutynin ER or tolterodine ER was the most recent OAB medication taken.
    • Patients without prior darifenacin treatment

Exclusion Criteria:

• • A mean daily urinary volume >3000 mL or a mean volume voided/micturition of >300 mL as verified in the micturition diary for two consecutive days prior to Baseline

  • Males with post-void residual (PVR) urinary volume >200 mL at Baseline
  • Clinically predominant and bothersome stress urinary incontinence, as determined by the investigator
  • Urinary retention or clinically significant bladder outlet obstruction as determined by the investigator

Other protocol-defined inclusion / exclusion criteria may apply