ORLANDO, Florida—Risedronate (Actonel^®) protects against osteoporotic fracture at a variety of anatomic sites, even when taken only 2 days per month, researchers reported at AACE 2008.

Nelson B. Watts, MD, and colleagues used historical control data to determine that taking risedronate 75 mg/day for 2 consecutive days of the month can significantly reduce vertebral fracture risk after 1 year.¹ “The antifracture efficacy of new osteoporosis therapies is usually based on placebo-controlled trials, but inclusion of a placebo arm in subsequent clinical trials may be limited by practical or ethical considerations. In these cases, use of historical controls can be explored as an interesting alternative,” Dr. Watts explained.

The researchers matched fracture data in an active-controlled study of risedronate dosing regimens (the 2CD study) with matched historical controls from previous placebo-controlled trials.

In patients treated with risedronate 75 mg/day for 2 days/month, new vertebral fractures were reduced by 79% relative to historical placebo group controls over 1 year of treatment. According to Dr. Watts, this was similar to the 1-year risk reduction seen with daily 5 mg risedronate (61%-65%).

“Risedronate 75 mg for 2 consecutive days each month appears as effective as the 5 mg daily dose in reducing the risk of new vertebral fractures in the first year of treatment,” Dr. Watts said.

Early, sustained nonvertebral fracture risk reduction

Andreas Grauer, MD, PhD, and colleagues² reported that, relative to placebo, risedronate reduced the risk for nonvertebral fracture by 1.8% after 6 months of treatment, and the magnitude of the difference increased during the first 2 years of treatment, remaining stable in the third year. The absolute risk reduction was 4%.

The researchers analyzed fractures in 1169 postmenopausal women with low bone mineral density (BMD) treated with at least one dose of either placebo or risedronate 5 mg/day. “These results confirmed the rapid reduction of nonvertebral fracture risk as early as month 6 with risedronate. Further, the risedronate antifracture efficacy was sustained throughout the remaining study period,” Dr. Grauer said.

Risedronate halves risk for repeat hip fracture in patients with low BMD

Additional work from Dr. Grauer's group showed that risedronate reduced the risk for repeat hip fracture.³ That analysis included 339 women aged 70 to 79 years, with low BMD, and a history of traumatic or an atraumatic hip fracture. Patients were treated with either placebo or risedronate 2.5mg or 5 mg daily. Over the 3-year study period, treatment with either dose of risedronate halved the risk ratio for clinical fracture compared with the placebo group (P <.05).

References

1. Watts NB, Brown J, Kline G, Delmas PD. Reduction of vertebral fracture risk at one year with two-consecutive 2 days-a-month risedronate 75 mg (2CD). Presented at: AACE 2008 annual meeting; May 14-17, 2008; Orlando, Fla. Presentation 511.
2. Grauer A, Roux C, Adachi JD, et al. Early and sustained non-vertebral fracture risk reduction with risedronate. Presented at: AACE 2008 annual meeting; May 14-17, 2008; Orlando, Fla. Presentation 517.
3. Grauer A, Zhou X, Miller PD, et al. The impact of risedronate on clinical fracture risk in patients with a prior hip fracture. Presented at: AACE 2008 annual meeting; May 14-17, 2008; Orlando, Fla. Presentation 518.