Once-Weekly Injection of Low-Dose Teriparatide (28.2 μg) Reduced the Risk of Vertebral Fracture in Patients with Primary Osteoporosis

We conducted a randomized, double-blind trial to assess the effect of 28.2 μg teriparatide versus placebo (1.4 μg teriparatide) on reduction of the incidence of vertebral fractures. Individuals enrolled in this study included patients with primary osteoporosis with one to five vertebral fractures and capable of self-supported walking. Attention was focused on incident vertebral fractures, change in bone mineral density (BMD) of the lumbar spine, and safety. A total of 316 subjects participated in the study, which lasted up to 131 weeks. Incident vertebral fractures occurred in 3.3 % of subjects in the 28.2 μg teriparatide-treated group and 12.6 % of subjects in the placebo group during the 78-weeks study period. Kaplan–Meier estimates of risk after 78 weeks were 7.5 and 22.2 % in the teriparatide and placebo groups, respectively, with a relative risk reduction of 66.4 % by teriparatide (P = 0.008). Lumbar BMD in the 28.2 μg teriparatide group increased significantly by 4.4 ± 4.7 % at 78 weeks, which was significantly higher than the corresponding data in the placebo group (P = 0.001). Adverse events were observed in 86.7 % of individuals in the teriparatide group and 86.1 % of those in the placebo group. In conclusion, weekly injection of a low-dose of teriparatide (28.2 μg) reduced the risk of incident vertebral fractures and increased lumbar BMD.