The duration of the trial will be approximately 69 weeks. This will include a 1-week Screening Period, an up to 12-week wash-off/titration /dose-stabilization period, a 2-week single-blind, placebo run-in period, a 52-week double-blind, placebo-controlled treatment period (including a 26-week Phase A and 26-week Phase B), and a post-treatment telephone contact 14 days after the last dose of blinded investigational product.