Alendronate increases bone density and bone strength at the distal radius in postmenopausal women

In addition to the alendronate Osteoporosis Intervention Trial (FOSIT) core protocol 901-0A of 1908 enrolled patients, the use of peripheral quantitat ive computed tomography (pQCT) was explored for the assessment of response to therapy, Bone mineral and strength related parameters at two different s ites at the distal radius were explored in a subset of the multicenter core study, One hundred and three patients were entered into the substudy and g iven either a daily dose of 10 mg of alendronate or placebo for 1 year. Mea surements were done at months 0, 3, 6, and 12, Inclusion criteria were bone mineral density (BMD) measurements at the lumbar spine of -2 SD. The respo nse to therapy was assessed by dual-energy X-ray absorptiometry in the lumb ar spine and the hip, and by pQCT in the ultradistal and the shaft sites of the radius. In line with the FOSIT core study, alendronate increased BMD a t the lumbar spine and the hip, and it decreased the serum biochemical mark ers of bone turnover. The substudy showed differences between the therapy a nd placebo group in trabecular bone density (8.4%, p = 0.095), in total den sity (6.8%, p = 0.009), and in the bone strength index (BSI) (15.6 mm(3), p = 0.037) at the ultradistal site due to treatment and no changes at the ra dius shaft, A significant correlation was observed between percentage chang es from baseline in BMD of the lumbar spine, and in total density and bone strength at the ultradistal radius site in the treatment group, but not in the placebo group. Thus, the ultradistal radius site did respond to alendro nate therapy. The increased bone density accompanied a significant gain in the BSI at the ultradistal site, a finding that might help explain the redu ced wrist fractures in the alendronate Fracture Intervention Trial.