Risedronate prevents bone loss in early postmenopausal women: a prospective randomized, placebo-controlled trial.

OBJECTIVES: To assess the efficacy and tolerability of risedronate, a pyridinyl bisphosphonate, in preventing loss of bone mineral density (BMD) of the lumbar spine and proximal femur in early postmenopausal women. METHODS: A total of 383 patients were randomly assigned to receive risedronate 2.5 or 5 mg or placebo once daily for 24 months. All patients received 1 g elemental calcium daily. BMD was measured by dual X-ray absorptiometry at baseline and at 3, 6, 12, 18, and 24 months. RESULTS: Risedronate 5 mg significantly increased BMD at the lumbar spine and femoral neck and trochanter in early postmenopausal women. Significant results were observed as early as 3 months. In the control calcium-supplemented group, BMD decreased steadily at each site throughout the study. The mean percentage change from baseline in BMD in the risedronate 5 mg group was significantly different from that in the control group at each determination at each site. At 24 months, the differences were 4.5 +/- 0.45% at the lumbar spine, 3.3 +/- 0.49% at the femoral neck, and 4.3 +/- 0.67% at the femoral trochanter. Risedronate 2.5 mg maintained BMD at each site, although the effect was less pronounced than that of risedronate 5 mg. Risedronate was well tolerated and was not associated with an increased incidence of overall or upper gastrointestinal adverse events. CONCLUSIONS: Risedronate 5 mg prevents bone loss in early postmenopausal women, is well tolerated, and represents an effective choice to maintain bone mass and prevent osteoporosis.