Investigation of Tolterodine, Pregabalin and a Tolterodine - Pregabalin Combination for the Treatment of Overactive Bladder

Inclusion Criteria: * Women \> 18 years Old * Diagnosis of OAB (micturition frequency \>/= 8 times per day; urinary urgency \>/= 4 times per week) Exclusion Criteria: * Subjects with symptoms of overactive bladder for less than 6 months prior to randomization. * Significant stress incontinence as determined by the investigator e.g. stress predominant mixed incontinence, positive cough provocation test. * Subjects with any condition that would contraindicate the use of tolterodine or pregabalin, including: Uncontrolled narrow angle glaucoma; Urinary retention; Myasthenia gravis; Gastric retention; Severe ulcerative colitis; Toxic megacolon; Rare hereditary problems of galactose intolerance; Fructose intolerance; Sucrose-isomalate insufficiency; Lapp lactase deficiency; Glucose-galactose malabsorption.