Dose Finding Study to Treat High Phosphate Levels in the Blood.

The study consists of a screening period of approximately 1 week, a wash out period of up to 3 weeks, where existing phosphate lowering medication is withheld, a 4-week treatment period and a follow-up period of up to 2 weeks, during which patients are put back on their pre washout phosphate lowering medication. The wash out period will be either 1 week, 2 weeks or 3 weeks depending on the increase in s-phosphate levels. There are 7 parallel treatment arms in the study with bid and od treatment regimens. Laboratory efficacy endpoints and safety assessments will be evaluated at various times throughout the study. The target population of the study is: male or female patients, above18 years of age with End Stage Renal Disease (ESRD) on chronic maintenance hemodialysis (HD) 3 times a week for a minimum of 3 months.