Alendronate in early postmenopausal women: Effects on bone mass during long-term treatment and after withdrawal

We studied the effect on bone mass of alendronate treatment for 5 yr and it s withdrawal. Four hundred and forty-seven postmenopausal women with normal bone mass entered a 3-yr randomized trial followed by a 2-yr open label ex tension. Three hundred and eleven women completed the first 3 yr, and 263 c onsented to continue and completed the extension. We are reporting data fro m groups using the dose of alendronate currently approved for osteoporosis prevention (5 mg) or from the group in which alendronate treatment was with drawn: 52 women received alendronate (5 mg) for 5 yr (group I), 56 received 3 yr of placebo followed by alendronate (5 mg) for 2 yr (group II), and 52 received alendronate (20 mg) for 2 yr followed by 3 yr off therapy (group III). In group I, alendronate (5 mg) increased bone mineral density (BMD) a t the spine and trochanter by 2.5-3.2% (P < 0.001 vs. baseline) and stabili zed total body and femoral neck BMD (change vs. baseline, P = NS) over 5 yr . By the end of 5 yr, BMD was comparable at the spine, hip, and total body in groups I and III. The 3-yr decrease in BMD after withdrawal of alendrona te (20 mg) in group III was 1.8-5.7% (P < 0.01 vs, baseline) and similar to the 3-yr decrease in BMD in group II during the initial 3 yr. In conclusio n, alendronate (5 mg) for 5 yr or alendronate (20 mg) for 2 yr followed by 3 yr off therapy prevented postmenopausal bone lass. After withdrawal of al endronate (20 mg), bone loss resumed at the normal early postmenopausalrate .