The purpose of this study is to determine if calcium acetate (PhosLo) can control serum phosphorus in pre-dialysis patients with moderate to severe impairment of kidney function.

In patients with impaired kidney function, dietary phosphorus can not be completely excreted, which leads to elevated levels of serum phosphorus. Elevated serum phosphorus leads to increased levels of parathyroid hormone (PTH), and is associated with bone disease and other adverse consequences such as soft-tissue and vascular calcification, and increased morbidity and mortality. It is therefore important to prevent hyperphosphatemia and maintain serum phosphorus levels within the range recommended by K/DOQI. In patients on dialysis, phosphate binders are routinely used to control serum phosphorus by absorbing dietary phosphate during the transit through the intestine. However, the use of phosphate binders for non-dialyzed patients with chronic kidney disease (CKD) is not an FDA approved indication, although some physicians treat patients prior to dialysis based on clinical judgment. The goal of this study is to demonstrate the efficacy of calcium acetate (PhosLo) in controlling serum phosphorus in patients with moderate to severe decrease in kidney function.

Inclusion Criteria:

• Non-dialyzed male or female patients with CKD, with a GFR of less than 30mL/min/1.73m² who have elevated serum phosphorus or who develop elevated serum phosphorus following washout from phosphorus-binding therapy.
• Patients must have written informed consent
• Negative serum pregnancy test if appropriate
• Expected to be able to comply with protocol procedures and schedule

Exclusion Criteria:

• Unstable angina pectoris
• Severe congestive heart failure
• Severe liver dysfunction
• Severe malnutrition
• Severe hyperparathyroidism
• AIDS (HIV positive subjects without AIDS are not excluded)
• Active malignancy for which the subject is receiving chemotherapy or radiation
• Subject unlikely to complete the study
• History of obstructed bowels or hypersensitivity to any of the study medications or their components
• History of swallowing disorders such as dysphagia (that would prevent the subject from taking the study drug) severe gastrointestinal motility disorders, or major GI tract surgery
• Participation in an investigational drug or device trial within 30 days of randomization
• Subjects on Vitamin D therapy
• Subjects with acute symptoms, in the last month, or current radiographic evidence of kidney stones
• Subjects who have undergone renal transplant or receiving dialysis
• Or any condition with makes patient participation not in the patients best interest