The symptom score for determining eligibility will be established during the Screening Period (up to 4 weeks) and eligible patients will be randomly allocated in a 2:1 ratio between the active and placebo arms at the baseline visit (Week 0). During the Treatment Period, clinic visits will occur at the end of Weeks 1, 3, 5 and 7. Following completion of the Treatment Period, patients will enter a 2-week Washout Period in both treatment arms.