A Study to Evaluate Add on Effect of Solifenacin in Men With Overactive Bladder Symptoms After Tamsulosin Monotherapy for 4 Weeks

Inclusion Criteria: * IPSS ≥ 12 * Symptoms of OAB as verified by the V8 (≥8) * Symptoms of OAB as verified by the screening 3-day bladder diary, defined by: * Mean urinary frequency ≥8 times/24 hours * Mean number of micturition-related urgency episodes ≥3 episode/24 hours (with a Urinary Sensation Scale rating of ≥3 marked for the corresponding micturition in the bladder diary) Exclusion Criteria: * Treatment within the 14 days preceding treatment with any alpha blocker drugs * A known history of bladder outlet obstruction due to: bladder neck contracture, clinical suspicion of prostate carcinoma, mullerian duct cysts, urethral obstruction due to stricture/valves/sclerosis or urethral tumor