The main purpose of this study is to evaluate the effects of teriparatide with those of alendronate on spine bone mineral density (BMD) and other osteoporosis factors in postmenopausal women with osteoporosis.

Inclusion Criteria:

• Postmenopausal women with osteoporosis.
• Ambulatory, 5 years or more past menopause.
• BMD T score between -2.5 and -4.0 at the lumbar spine or femoral neck.
• Normal or clinically insignificant abnormal laboratory values, including serum calcium, parathyroid hormone (PTH) 1-84, 25-hydroxyvitamin D, and alkaline phosphatase.

Exclusion Criteria:

• Prior treatment with PTH or a PTH analogue.
• Treatment with bisphosphonates within 12 months, anabolic corticosteroids or calcitriol or vitamin D analogues or agonists within 6 months, estrogens or selective estrogen receptor modulators within 3 months, or calcitonin within 2 months; therapeutic doses of fluoride; systemic corticosteroid use within 1 month or for more than 30 days in the prior year; use of anticoagulants within 1 month.
• History of diseases other than postmenopausal osteoporosis that affect bone metabolism.
• History of an increased risk of osteosarcoma (ie, patients with Paget disease of bone, previous skeletal exposure to external beam radiotherapy, or previous malignant neoplasm involving the skeleton).
• Malignant neoplasms within 5 years; carcinoma in situ of the uterine cervix within 1 year.
• Nephrolithiasis or urolithiasis within 2 years, or impaired renal function.
• Abnormal uncorrected thyroid function.
• Liver disease or clinical jaundice.
• Alcohol or other drug abuse.
• Poor medical or psychiatric risk for treatment.