Monthly dosing of 75 mg risedronate on 2 consecutive days a month: efficacy and safety results

SUMMARY: Postmenopausal women with osteoporosis received 75 mg risedronate on two consecutive days each month or 5 mg daily for 12 months. Changes in bone mineral density and bone turnover markers were similar between treatments. Risedronate 75 mg twice monthly was effective and safe suggesting a new, convenient dosing schedule. INTRODUCTION: Patients perceive less frequent dosing as being more convenient. This 2-year trial evaluates the efficacy and safety of a new monthly oral regimen of risedronate; 1 year results are presented here. METHODS: Postmenopausal women with osteoporosis (n = 1229) were randomly assigned to double-blind treatment with 75 mg risedronate on two consecutive days each month (2CDM), or 5 mg daily. The primary endpoint was the percent change from baseline in lumbar spine (LS) bone mineral density (BMD) at month 12. Secondary efficacy was evaluated by mean percent changes from baseline in BMD in LS, total hip, trochanter, and femoral neck, and bone turnover markers (BTMs). RESULTS: Risedronate 75 mg 2CDM was non-inferior to 5 mg daily (treatment difference 0.21; 95% CI -0.19 to 0.62). Mean percent change in LS-BMD was 3.4% +/- 0.16 and 3.6% +/- 0.15 respectively. Mean percent changes in BMD and BTMs were significant and similar for both treatment groups. New vertebral fractures occurred in 1% of subjects with either treatment. Both treatments were generally well tolerated and safe. CONCLUSIONS: Risedronate 75 mg 2CDM was non-inferior in efficacy and did not show a difference in safety vs. 5 mg daily after 12 months, leading to a similar benefit.