Screening will be conducted on an outpatient basis within 21 days prior to the Baseline visit. Patients meeting the inclusion/exclusion criteria at the Baseline visit will enter the Treatment Phase and begin taking one BPS-MR tablet (60µg) b.i.d. and escalating by one tablet b.i.d. each week to a maximum dose of 600µg (ten tablets) b.i.d. or until the patient reaches an intolerable dose.