Inclusion Criteria:

• Patient has a spine or hip anatomy suitable for dual-energy x-ray absorptiometry
• Patient has been postmenopausal defined as
  • A) greater than and equal to 1 year beyond the lmp (last menstrual period) in women greater than and equal to 50 years of age with who did not received hysterectomy
  • B) serum fsh greater than and equal to 30 iu/l in women who underwent hysterectomy
  • C) post bilateral oophorectomy
• Patient has serum 25(oh)d greater than and equal to 9 ng/ml.
• Patient with mean serum 25(oh)d is greater than and equal to 9 ng/ml, but not higher than 15 ng/ml (in 2 assay) is required to have serum pth and total alkaline phosphatase within the reference range
• Patient is suitable for treatment with oral bisphosphonate.
• Patient meets one of the following:
  • A) patient is a candidate for osteoporosis therapy with bisphosphonates, has bmd t-score less than and equal to 2.5 at at least one of testing locations including total hip, spine and femoral neck,
  • B) patient is a candidate for osteoporosis therapy (bisphosphonates, strontium, or pth), has bmd t-score less than and equal to 2.0 and have 1 prior vertebral fracture (l1-l4),
  • C) patient is a candidate for osteoporosis therapy (bisphosphonates, strontium, or pth), have greater than and equal to 2 prior vertebral fracture (l1-l4), or note: eligibility for this criterion is based on spine or femoral (neck or total) bmd
• Patient understands the study procedures, alternative treatments available and risks involved with the study, and voluntarily agrees to use sun cream and limit direct solar exposure in a hour/day for 16 weeks and participate by giving a written informed consent
• Patient with pth higher than 72 ng/l at baseline will be excluded, however, a 10 % variance would be allowed

Exclusion criteria:

• Patient has or has had a history of malignancy or active systemic diseases less than 5 years prior to signing informed consent
• Patient with abnormalities of the esophagus that delay esophageal emptying