Alendronate for the prevention of bone mineral loss during gonadotropin-releasing hormone agonist therapy

OBJECTIVE: To evaluate alendronate as a prophylactic measure against bone mineral density (BMD) loss in reproductive-aged women receiving gonadotropin-releasing hormone agonist (GnRHa) therapy for 6 months. STUDY DESIGN: A randomized, double-blind, placebo-controlled, pilot trial at a university-affiliated community hospital. Subjects were 11 premenopausal women with indications for GnRHa therapy who were randomized to receive alendronate, 10 mg, or placebo, by mouth daily during 6 months of GnRHa use. Both groups received intramuscular depot leuprolide acetate, 3.75 mg every 28 days for a total of 24 weeks. BMD at the lumbar spine and femur was determined by dual energy x-ray absorptiometry at baseline and at the conclusion of treatment. Lipids and urinary N-telopeptide were measured before and during treatment. RESULTS: Alendronate-exposed subjects experienced a mean gain of 1.0% (P = .35) in lumbar BMD as compared to a significant mean loss in the control group 3.8% (P = .01). Subjects in the placebo group experienced a significant reduction in mean femur BMD of 3.4% (P = .02), while alendronate-exposed subjects had a loss of 0.4% (P = .65). Bone turnover, as evidenced by urinary N-telopeptide, increased over baseline for both groups. Neither group experienced significant changes in lipids during the study period. CONCLUSION: Alendronate appears to offer some degree of protection against BMD loss in young women during transient, induced hypoestrogenemia. Alendronate was associated with a gain in lumbar (trabecular) BMD but less than expected from studies of postmenopausal women. With the expectation that young women gain BMD, extending the safe and effective duration of GnRHa therapy in this population may require additional measures.