The Prevention of Early Postmenopausal Bone Loss by Cyclical Etidronate Therapy: A 2-Year, Double-blind, Placebo-Controlled Study

PURPOSE: To determine whether intermittent cyclical etidronate therapy can prevent early postmenopausal bone loss. PATIENTS AND METHOD: This was a 2-year outpatient, randomized, double-blind, placebo-controlled clinical trial. The subjects were 152 women within 1 to 10 years of the onset of menopause and bone mineral density (BMD) between 0 and −2 SD of normal values for a 50 year old woman. The women were stratified according to years since the menopause (1 to 3 years: n = 43; 4 to 6 years: n = 53; 7 to 10 years: n = 56). Measurements of lumbar spine, proximal femur and total body BMD were performed at baseline, 12 and 24 months by dual x-ray absorptiometry. Biochemical markers of bone resorption and bone formation were measured on the same visits. RESULTS: One hundred thirty-five subjects completed the study. Mean percentage change in lumbar spine BMD (and SEM) at 2 years was +2.14 (0.47)% in the etidronate group and −1.72 (0.41)% in the placebo group. Results for lumbar spine BMD in the treated and control groups stratified according to years since the menopause were: 1 to 3 years: +1.73 (0.84)% and −3.30 (0.70)%; 4 to 6 years: +1.37 (0.88)% and −1.80 (0.61)%; 7 to 10 years: +3.42 (0.61)% and −0.38 (0.70)%. The effect of both treatment group and menopausal stratum were highly statistically significant for lumbar spine and total body BMD. Treatment group, but not stratum, was significant for BMD in the proximal femur. Markers of bone resorption and bone formation were significantly decreased by etidronate therapy. CONCLUSIONS: Cyclical etidronate prevents bone loss in the total skeleton and at the clinically relevant sites (spine and proximal femur) even in the early postmenopausal years. Hence, it appears to be an effective and safe nonhormonal therapy in postmenopausal women with normal or low BMD.