Efficacy & Safety Study of VESIcare® (Solifenacin Succinate) in Patients Wishing to Switch From Detrol LA® for Treatment of Overactive Bladder

Inclusion Criteria: * Patients with OAB who have been treated with tolterodine tartrate extended release for at least 4 weeks immediately preceding entry into the study, and wish to switch to solifenacin succinate due to lack of sufficient improvement in urgency episodes. * Previous non-drug treatment of OAB is allowed if it has been established at least 4 weeks prior to Screening and is continued throughout the study. * At least 3 urinary urgency episodes/24 hours while receiving tolterodine tartrate extended release documented in a 3-day patient diary in the pre-washout assessments on tolterodine tartrate extended release with or without urge incontinence described as OAB syndrome. * Prior to treatment with tolterodine tartrate extended release, patients must have had OAB syndrome for 3 or more months. Exclusion Criteria: * Previous treatment with darifenacin * Treatment with tolterodine tartrate extended release for less than 4 weeks prior to enrollment in the study. * Significant stress incontinence or mixed stress/urge incontinence where stress is the predominant factor as determined by the investigator. * Evidence of a urinary tract infection; chronic inflammation such as interstitial cystitis and bladder stones. * Clinically significant outflow obstruction as determined by the Investigator * Uncontrolled narrow angle glaucoma, urinary or gastric retention. * All patients with severe renal or hepatic impairment will be excluded * Patients with chronic severe constipation or history of diagnosed gastrointestinal obstructive disease.