Alendronate prevents postmenopausal bone loss in women without osteoporosis. A double-blind, randomized, controlled trial. Alendronate Osteoporosis Prevention Study Group

BACKGROUND: Preventing bone loss associated with menopause and aging and maintaining the normal micro-architecture of bone provide important opportunities for the prevention of osteoporosis and fractures.

OBJECTIVE: To determine the safety and efficacy of alendronate, an aminobisphosphonate, for preventing postmenopausal bone loss.

DESIGN: 3-year double-blind, randomized, placebo-controlled trial.

SETTING: 15 osteoporosis centers throughout the world.

PARTICIPANTS: 447 women who had recently experienced menopause (6 to 36 months before study entry).

INTERVENTION: Participants were randomly assigned to one of five regimens: oral placebo; oral alendronate, 1, 5, or 10 mg/d; or oral alendronate, 20 mg/d for 2 years followed by placebo during the third year (20/0 mg/d).

MEASUREMENTS: Bone mineral density was measured by dual-energy x-ray absorptiometry. Bone turnover and bone quality were assessed with biochemical markers and bone histomorphometry.

RESULTS: Alendronate at 5, 10, and 20/0 mg/d increased bone mineral density from baseline at the lumbar spine, femoral neck, and trochanter by 1% to 4% and in the total body by 0.3% to 1.0%; placebo led to losses of 2% to 4% at these sites. Alendronate, 1 mg/d, attenuated losses relative to those seen with placebo. Alendronate decreased markers of bone resorption to a new steady state by 3 months and decreased markers of bone formation by 6 to 12 months. Bone quality remained normal. At all dosages studied, alendronate had a safety and tolerability profile similar to that of placebo.

CONCLUSIONS: In early postmenopausal women, alendronate given for 3 years at dosages of 5 mg/d or greater prevented the loss of bone mineral density at the spine and hip and in the total body. Alendronate seems to be a safe and effective nonhormonal option for prevention of postmenopausal bone loss.