A Study of Zemplar® Injection and Hectorol® Injection on Intestinal Absorption of Calcium in Chronic Kidney Disease

Inclusion Criteria

• Subject is >= 20 years of age.
• Subject is diagnosed with CKD Stage 5, and must be on maintenance (chronic) hemodialysis (HD) three times a week for at least 2 months prior to the Screening Visit and expected to remain on HD for the duration of the study.
• If female, subject is either not of childbearing potential, defined as postmenopausal for at least 1 year or surgically sterile (bilateral tubal ligation, bilateral oophorectomy or hysterectomy), or is of childbearing potential and practicing one of the following methods of birth control:
• Condoms, sponge, foams, jellies, diaphragm or intrauterine device (IUD)
• Contraceptives (oral or parenteral) for three months prior to study drug administration
• In a monogamous relationship with a vasectomized partner
• If female, subject is not breastfeeding and has a negative serum pregnancy test prior to the treatment phase.
• Subject has an intact PTH value > 200 pg/mL at Screening only (or Re-screening, if applicable).
• Subject has a serum calcium level 2 times the upper limit of normal for liver enzyme (SGOT/AST, SGPT/ALT) levels.
• Subject has a hemoglobin level 5 mg prednisone daily, or other drugs that may affect calcium or bone metabolism within 2 weeks prior to screening, other than females on stable (same dose and product for 3 months) estrogen and/or progestin therapy.
• For any reason, subject is considered by the Investigator to be an unsuitable candidate to receive pharmacological doses of vitamin D.
• Subject has received any investigational drug within 4 weeks prior to the Treatment Phase.