This is a double-blind, randomized, cross-over study conducted at centers within the United States. The study consists of five periods: an up to two-week Screening Period, a 5-week Run-In Period, two eight-week study treatment periods and a two-week Washout Period. Patients are assigned randomly (1:1) to one of two treatment sequences: sevelamer carbonate for eight weeks followed by sevelamer hydrochloride for eight weeks or sevelamer hydrochloride for eight weeks followed by sevelamer carbonate for eight weeks

The study was conducted at 15 centers (2 of which did not enroll any patients). A total of 79 hemodialysis patients were assigned randomly to one of two treatment sequences.

Inclusion Criteria:

• patient had received hemodialysis three times per week for 3 months or longer;
• patients were maintained on sevelamer hydrochloride as their primary phosphate binder with a total daily dose of ≤ 13.6 g with serum phosphorus concentrations at the last two measurements between 3.0 and 6.5 mg/dL, the most recent iPTH ≤ 600 pg/mL and the most recent serum calcium within the normal range.

Exclusion Criteria:

• if patient had active bowel obstruction, dysphagia, swallowing disorders, or severe gastrointestinal motility disorders;
• active ethanol or drug abuse (excluding tobacco);
• need for antidysrhythmic or antiseizure medications used to control these conditions;
• poorly controlled diabetes mellitus or hypertension;
• active vasculitis;
• active malignancy other than basal-cell carcinoma;
• HIV infection; or
• any clinically significant unstable medical condition as judge by the Investigator.