Safety and Efficacy of Zemplar Capsule in Reducing Serum iPTH Levels in Chronic Kidney Disease Subjects (Three Times Weekly)

Inclusion Criteria: * 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 Exclusion Criteria: * 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 mos. 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