Alendronate prevents loss of bone density associated with discontinuation of hormone replacement therapy: a randomized controlled trial.

BACKGROUND Many women using hormone replacement therapy (HRT) will discontinue HRT and lose its bone-protective effect. Methods to preserve bone density in these women need to be explored. This multicenter, international, randomized, blinded, 12-month study was conducted to assess the effect of alendronate sodium on bone density in women who had recently discontinued HRT. METHODS The 144 postmenopausal women included in the study were diagnosed as having low bone mineral density (BMD) and had recently discontinued HRT. They were randomized to receive either a daily dose of 10 mg of alendronate sodium or matching placebo. The main outcome measures were spine, hip, and total body BMD; biochemical markers of bone turnover; and tolerability. RESULTS Alendronate treatment was associated with a 2.3% mean increase (95% confidence interval [CI], 1.7%-3.0%) in spine BMD compared with a mean loss of 3.2% (95% CI, - 4.6% to - 1.7%) in patients receiving placebo, for a difference of 5.5% (95% CI, 4.2%-6.8%) between alendronate and placebo. Greater hip and total body BMD preservation was also observed with alendronate use. Bone turnover decreased significantly with alendronate (bone-specific alkaline phosphatase levels decreased by 20% and urinary N-telopeptide/creatinine ratio by 47%), but increased in the placebo group (by 18% and 36%, respectively). Alendronate was well tolerated, with no increase in adverse events compared with placebo. CONCLUSIONS A high rate of bone loss was observed in the first 12 to 15 months after discontinuation of HRT in postmenopausal women with low BMD. Treatment with alendronate increased or maintained both spine and hip BMD and prevented the increase in bone resorption seen with withdrawal of HRT in this population.