Safety Study of an Oral Vitamin D Analog in Postmenopausal Women

Inclusion Criteria: 1. Normal healthy postmenopausal women, ≥ 60 but ≤ 80 years of age, or between 45 and 60 years of age who have been amenorrheic for at least 2 years plus have a serum FSH level of \> 30 IU/L, or women with a documented bilateral oophorectomy at least 2 years prior to study start. 2. Within ±30% of their ideal body weight for height and body frame. 3. Demonstrated ability to understand and willingness to sign an Informed Consent Form. 4. 24-hour urinary Ca ≤250 mg/day and a urinary Ca:Cr ≤0.35. 5. Negative urine test for selected drugs of abuse. 6. Willing to maintain a total calcium intake between 700 and 1000 mg/day. Exclusion Criteria: 1. Any acute or chronic condition that would limit the subject's ability to complete the study. 2. Active clinical manifestations of significant metabolic, hematological, pulmonary, hepatic, cardiovascular, gastrointestinal (including malabsorption), neurological, renal, urological or psychiatric disorders. 3. History or presence of any diseases known or believed to influence calcium absorption or metabolism. 4. History of renal calculi. 5. History of an eating disorder. 6. History of stomach or intestinal surgery. 7. History of hypersensitivity or allergies to any vitamin D derivative. 8. History or presence of an abnormal ECG. 9. Use of any medications or products affecting vitamin D metabolism within 6 months prior to study entry. 10. Use of any medications or products affecting calcium balance or bone turnover within 6 months prior to study entry. 11. Participation in any other investigational study drug trial in which receipt of investigational study drug occurred within 60 days prior to study entry. 12. Use of vitamin and/or mineral supplements \>1X RDI within 4 weeks prior to study entry, unless deemed acceptable by Investigator. 13. Poor peripheral venous access. 14. Receipt of blood products within 2 months prior to study entry. \-