The purpose of this study is to determine if sevelamer carbonate powder is an effective treatment for the control of serum phosphorous levels in patients on dialysis when compared to sevelamer hydrochloride tablets.

Inclusion Criteria:

• Receiving three times per week haemodialysis for three months or longer.

• Taking sevelamer hydrochloride alone (e.g. not using other types of phosphate binders concomitantly) or on combination therapy (e.g. using sevelamer hydrochloride and calcium containing, or metal phosphate binders concomitantly) not exceeding a total daily binder dose of 14.4 g, for at least 60 days prior to screening.

• Have the following documented local laboratory measurements:

  1. Two most recent consecutive serum phosphorus measurements that are ≥ 3.0 and ≤ 7.0 mg/dL (≥ 0.96 and ≤ 2.26 mmol/L) within 60 days of screening
  2. An most recent iPTH measurement ≤ 900 pg/mL (< 99 pmol/L) within 90 days of screening
  3. A most recent serum calcium (adjusted for albumin) measurement within normal range defined by the local laboratory within 60 days of screening

• Have the following central laboratory measurements:

  1. A serum phosphorus measurement ≥ 5.5 mg/dL (≥ 1.76 mmol/L) at Visit 2 (after Washout)
  2. A serum iPTH measurement ≤ 800 pg/mL at Visit 5 (prior to randomization)
  3. A serum phosphorus measurement ≥ 3.0 and ≤ 6.5 mg/dL (≥ 0.96 and ≤ 2.08 mmol/L) at Visit 5

• If on vitamin D replacement or calcimimetics therapy, be at a stable dose for at least one month prior to screening and willing to maintain the same dose throughout the duration of the study, except for safety reasons.

• Willing to maintain screening doses of lipid medication for the duration of the study, except for safety reasons.

• Willing to avoid any intentional changes in diet such as fasting or dieting.

• If female and of childbearing potential (pre-menopausal and not surgically sterile), willing to use an effective contraceptive method throughout study, which includes barrier methods, hormones, or intrauterine devices (IUDs).

• Willing to stop all calcium supplements not prescribed by the investigator including multivitamins containing calcium.

• Willing to refrain from using aluminium, calcium, lanthanum, or magnesium containing antacids throughout duration of the study unless prescribed by the investigator as a calcium supplement per protocol.

• Have a level of understanding and willingness to cooperate with all visits and procedures, including telephone contacts, as described in the consent by the study site personnel.

Exclusion Criteria:

• Have poorly controlled diabetes mellitus or hypertension, active vasculitis, HIV infection, or any clinically significant unstable medical condition (defined by investigator).
• Have active dysphagia, swallowing disorders, bowel obstruction, or severe gastrointestinal motility disorders.
• Have participated in a study of an investigational drug during the 30 days preceding the start of the screening period.
• Has active ethanol or drug dependence or abuse, excluding tobacco use.
• Have any other condition, which, in the investigator's opinion, will prohibit the patient's participation in the study.
• If female, be pregnant or breast-feeding.
• Have any evidence of active malignancy except for basal cell carcinoma of the skin. A history of malignancy is not an exclusion.
• Use of anti-arrhythmic or anti-seizure medications for arrhythmia or seizure disorders.
• Have a known hypersensitivity to sevelamer or any of its constituents.
• Have a poor record of compliance with medication.