Pharmacokinetics of a Single 14C-labeled Dose of Risedronate or Alendronate Followed by Once-a-week Unlabeled Oral Dose

Inclusion Criteria: * have medical history documentation verifying postmenopausal status of at least 2 years (natural or surgical). If not documented, confirmation will be required using estradiol \< 20 pg/mL and follicle stimulating hormone (FSH) \> 40 IU/mL; * have osteopenia or osteoporosis (\< 1.002 g/cm2 Lunar or \< 0.882 g/cm2 Hologic) as determined by DXA of the lumbar spine (AP or PA view, L1-L4). This corresponds to a T-score of approximately \< -1.5. Exclusion Criteria: * any clinically significant out-of-range laboratory values and vital signs, * a clinically significant cardiovascular, hepatic, renal, or parathyroid disease, in the opinion of the Investigator * a known hypersensitivity to bisphosphonates