Abstract
Context:Odanacatib, a cathepsin K inhibitor, increases spine and hip areal bone mineral density (BMD) in postmenopausal women with low BMD and cortical thickness in ovariectomized monkeys.Objective:The objective of the study was to examine the impact of odanacatib on the trabecular and cortical bone compartments and estimated strength at the hip and spine.Design:This was a randomized, double-blind, 2-year trial.Setting:The study was conducted at a private or institutional practice.Participants:Participants included 214 postmenopausal women with low areal BMD.Intervention:The intervention included odanacatib 50 mg or placebo weekly.Main Outcome Measures:Changes in areal BMD by dual-energy x-ray absorptiometry (primary end point, 1 year areal BMD change at lumbar spine), bone turnover markers, volumetric BMD by quantitative computed tomography (QCT), and bone strength estimated by finite element analysis were measured.Results:Year 1 lumbar spine areal BMD percent change from baseline was 3.5% greater with odanacatib than placebo (P <.001). Bone-resorption marker C-telopeptide of type 1 collagen was significantly lower with odanacatib vs placebo at 6 months and 2 years (P <.001). Bone-formation marker procollagen I N-terminal peptide initially decreased with odanacatib but by 2 years did not differ from placebo. After 6 months, odanacatib-treated women had greater increases in trabecular volumetric BMD and estimated compressive strength at the spine and integral and trabecular volumetric BMD and estimated strength at the hip (P <.001). At the cortical envelope of the femoral neck, bone mineral content, thickness, volume, and cross-sectional area also increased from baseline with odanacatib vs placebo (P <.001 at 24 months). Adverse experiences were similar between groups.Conclusions:Over 2 years, odanacatib decreased bone resorption, maintained bone formation, increased areal and volumetric BMD, and increased estimated bone strength at both the hip and spine.