A Research Study for Patients With End-Stage Renal Disease (ESRD)

Inclusion Criteria: * ESRD patients requiring maintenance dialysis (haemodialysis, haemodiafiltration, haemofiltration, or peritoneal dialysis) for at least 1 month * The mean of 2 iPTH determinations within 21 days before randomization and drawn at least 2 days apart must be greater than or equal to 300 pg/mL (31.8 pmol/L) and less than 800 pg/mL (84.8 pmol/L). If biPTH is determined, the mean levels must be greater than or equal to 150 pg/mL (15.9 pmol/L) and less than 410 pg/mL (43.5 pmol/L) * The mean of 2 serum calcium determinations (corrected for albumin) drawn on the same day as the PTH determinations must be greater than or equal to 8.4 mg/dL (2.1 mmol/L) Exclusion Criteria: * Have an unstable medical condition, defined as having been hospitalised, other than for dialysis vascular access revision, within 30 days before day 1, or otherwise unstable in the judgment of the investigator * Have had a parathyroidectomy in the 6 months before day 1 * Have received vitamin D therapy for less than 21 days before day 1 or required a change in prescribed vitamin D brand or dose within 21 days before day 1. If subjects are not prescribed vitamin D therapy, they must remain free of vitamin D therapy for the 21 days before day 1. * Received, within 21 days before day 1 of the dose titration phase, therapy with medications that are predominantly metabolized by the enzyme CYP2D6 and have a narrow therapeutic index (e.g., flecainide, vinblastine, thioridazine, and most tricyclic antidepressants). The tricyclic antidepressant amitriptyline is permitted. - Experienced a myocardial infarction within 3 months prior to day 1 * Are currently enrolled in, or have not yet completed at least 30 days before day 1, other invasive investigational device or investigational drug trials, or are receiving other investigational agents (experimental dialysis machines are acceptable) * Have a gastrointestinal disorder that may be associated with impaired absorption or orally administered medications or an inability to swallow tablets