Safety and Efficacy of Zemplar Capsule in Reducing Serum iPTH Levels in Chronic Kidney Disease Subjects (Daily Dosing)

- Under care of physician at least 2 months (for CKD) - Not on active Vitamin D therapy for at least 4 weeks prior - If female: - Not of childbearing potential, OR, - Practicing birth control - Not breastfeeding - If taking phosphate binders, on a stable regimen at least 4 weeks prior - For entry into Pretreatment Phase: - iPTH at least 120 pg/mL - GFR of 15-60 mL/min and no dialysis expected for at least 6 months - For entry into Treatment Phase: - Average of 2 consecutive iPTH values of at least 150 pg/mL, taken at least 1 day apart (all values not less than 120 pg/mL_ - 2 consecutive corrected serum calcium levels between 8.0-10.0 mg/dL - 2 consecutive serum phosphorus levels of not more than 5.2 mg/mL

- History of allergic reaction or sensitivity to similar drugs - Acute Renal Failure within 12 weeks of study - Chronic gastrointestinal disease - Spot urine result demonstrating a urine-calcium-to-urine creatinine ratio of greater than 0,2, or a history of renal stones - Taken aluminum-containing phosphate binders within last 12 weeks, or requires such medication for more than 3 weeks during study - Current malignancy, or clinically significant liver disease - Active granulomatous disease (TB, sarcoidosis, etc.) - History of drug or alcohol abuse within 6 months prior - Evidence of poor compliance with diet or medication - Received any investigational drug or participated in any device trial within 30 days prior - Taking maintenance calcitonin, bisphosphonates, or drugs that may affect calcium or bone metabolism (other than females on stable estrogen and/or progestin therapy) - On glucocorticoids for a period of more than 14 days within the last 6 months - HIV positive