Specifically, the maximum change from baseline in PINP and CTx was seen at 6 months; this was followed by a decrease in bone marker levels but, at 18 months, the level of PINP remained increased relative to baseline. This pattern of change in serum PINP levels has been observed in other studies of teriparatide-treated patients with GIO [36, 56], in postmenopausal women with osteoporosis [18, 42], and in men with osteoporosis [13]. Moreover, the absolute change from baseline in PINP at every time point in our study was well above the least significant change determined previously (10 μg/l) and used to monitor the early response PF-6463922 to teriparatide treatment [21, 55].

Although our study has several important strengths, such as the prospective design in a group of patients with osteoporosis who have scarcely been evaluated in clinical trials, the application for the first time of novel HRQCT-based FE analysis in men with GIO, and a MMRM analysis

adjusted for factors such as age, prior fracture, duration of prior bisphosphonate use and GC dose, it also has some limitations. These include that the analysis was restricted to only one vertebra (T12), but vertebral strength BIBW2992 chemical structure may vary along the spine. Second, the FE analysis assumes that bone tissue properties are constant for all patients during longitudinal treatment. However, since the patients involved in the study were GC users for several years, we do not expect a change in the local BMD–strength relationship in the course of the study. A hypothetical shift of the local BMD–strength relationship due to GC therapy throughout the study would influence neither the trends of the FE analysis nor the reported correlations. Aprepitant Other limitations of the study are that the duration of treatment was for 18 Selleckchem Idasanutlin months only and the limited sample size. Longer treatment may offer even more pronounced advantages

for both drugs. Although we only measured serum levels of PINP and CTx, these have recently been recommended as the reference markers of bone turnover to be used in clinical studies [1]. In conclusion, teriparatide at 20 μg/day demonstrated superior efficacy compared to risedronate 35 mg/week in the effects on biomechanical indices estimated by HRQCT-based FEA at the 12th thoracic vertebra in male patients with GIO. The changes from baseline in PINP revealed significant positive correlations with the changes in vertebral strength in all the loading modes at 18 months in the teriparatide group only. Changes in serum CTx showed fewer correlations. Serial spine QCT involves exposure to significant levels of radiation and considerable costs, which will limit its widespread use in normal clinical practice as an indicator of vertebral bone strength.