Effect of stopping risedronate after long-term treatment on bone turnover.

Context: Determining how quickly bisphosphonate treatment effects begin to regress is crucial when considering termination of treatment.

Objective: Our objective was to assess the effects of 1 yr discontinuation of risedronate use in postmenopausal women with osteoporosis who had previously received risedronate for 2 or 7 yr.

Design And Setting: Before initiation of the current study, placebo/5-mg-risedronate patients had received placebo for 5 yr and risedronate for 2 yr, whereas 5-mg-risedronate patients had received risedronate for a total of 7 yr. Risedronate was then discontinued for 1 yr (yr 8).

Patients: Postmenopausal women with osteoporosis who had previously completed the 3-yr Vertebral Efficacy with Risedronate Therapy MultiNational (VERT-MN) pivotal trial, plus a 2-yr extension comparing risedronate or placebo for a total of 5 yr, followed by 2 yr of open-label risedronate treatment were enrolled in these trial extensions.

Main Outcome Measures: Evaluations included changes in type I collagen cross-linked N-telopeptide (NTX)/creatinine (Cr) and bone mineral density (BMD) values, fracture incidence, and adverse events.

Results: After 1 yr of risedronate discontinuation, NTX/Cr levels increased toward baseline in both patient groups vs. the values at the end of yr 7. In both treatment groups, off-treatment total hip and femoral trochanter BMD values decreased, whereas lumbar spine and femoral neck BMD were maintained or slightly increased. The adverse event profiles were similar between the two treatment groups during yr 8.

Conclusions: One year of discontinuation of risedronate treatment in patients who had received 2 or 7 yr of risedronate therapy led to increases in NTX/Cr levels toward baseline and decreases in femoral trochanter and total hip BMD.