Postmenopausal osteoporosis is a bone disease characterized by the loss of too much bone from the body after menopause. Odanacatib is a cathepsin K inhibitor that reduces bone resorption and maintains bone formation. The objective of this study is to examine the efficacy and safety of odanacatib in reducing fracture risk in women with postmenopausal osteoporosis.

This multicenter, double-blind, event-driven, randomized, placebo-controlled trial that included a total of 16,071 patients aged 65 or more who were postmenopausal for more than five years and had a femoral neck/hip bone density T-score between −2·5 and −4·0. The participants were randomly assigned in a 1:1 ratio to receive oral odanacatib (50 mg once per week, n=8,043) or matching placebo (n=8,028). The primary outcome of the study was the incidence of vertebral fractures after 6-12 months.

During the median follow-up of 47.6 months, the cumulative incidence of radiographic vertebral fractures was 3.7% in the odanacatib group, as compared with 7.8% in the placebo group. Similar trends were exhibited in the cumulative incidence of hip fractures (0.8% vs. 1.6%) and non-vertebral fractures (5.1% vs. 6.7%). However, odanacatib was associated with an increased risk of stroke (1.7%).

The research concluded that odanacatib reduced the overall risk of fractures in women with postmenopausal osteoporosis but was also associated with an increased risk of stroke.