PTH & Ibandronate Combination Study (PICS)

This randomized double-blind clinical trial for the treatment of postmenopausal osteoporosis will be conducted and coordinated by study investigators who also participated in the investigator-initiated PaTH study. Final data analysis will compare the results from this trial with those from the PaTH study. In the PaTH study, 238 women between 55 and 85 years of age were randomized to receive either: 1. PTH for 1 year followed by alendronate for 1 year 2. PTH and alendronate for 1 year followed by alendronate for 1 year 3. alendronate for 2 years 4. PTH for 1 year followed by placebo for 1 year. In the PICS 44 postmenopausal women between the ages of 55 to 75 years of age with osteoporosis who meet the inclusion/exclusion criteria,will be randomized to the following 2 treatment groups. Group A will received 6 months of monthly Ibandronate, plus daily PTH 1-84,100 μg; followed by 18 months of Ibandronate only. Group B will received 3 months of daily PTH 1-84,100 μg; followed by 9 months of monthly Ibandronate, over 2 years. Calcium (400-650 mg) and Vitamin D (400 IU) supplements will be provided to all participants. The primary objective is to determine if, at 3 months, the women treated with the concurrent combination of PTH and ibandronate (Group A) show a significant increase in bone marker formation compared to baseline (unlike the combination PTH/alendronate-treated women in PaTH). This will be accessed by examining the change in the markers P1NP, BSAP and serum CTX. As a secondary objective, we will compare the trabecular spine BMD measures of those treated with concurrent PTH/Ibandronate (Group A) to those who received 3 months of PTH followed by Ibandronate(Group B). Another secondary objective will be to compare changes between groups in trabecular bone and DXA spine BMD after 2 years of treatment. Changes to the fat content of the vertebrae during a course of PTH therapy will be examined using MRI spinal spectroscopy. Crosstabulation of these changes against changes in trabecular BMD, should indicate an effect on measurements. As well, the effect of a second three-month course of PTH therapy in Group B is of major interest.