An estradiol matrix transdermal system for the prevention of postmenopausal bone loss

Objective: The aim of this study was to evaluate the efficacy, safety, and tolerability of 2 years' application of an estradiol matrix transdermal system for the prevention of postmenopausal bone loss. Methods: In this multicenter, randomized, placebo-controlled, parallel-group study, 261 surgically or naturally postmenopausal women were randomized to apply the estradiol matrix transdermal system (0.025, 0.0375, 0.05, or 0.1 mg/d) or matching placebo twice a week for 2 years. The study was double blind with respect to treatment (active vs placebo) but not to the dose levels of active treatment (because of the differing sizes and shapes of the patches). In addition to receiving the assigned treatment, the 100 nonhysterectomized women received 2.5 mg medroxyprogesterone acetate daily throughout the study. Results: The evaluable group (n = 259) had a mean age of 52 years and a mean duration of menopause of 32 months. Following 2 years of treatment, there were significant differences in favor of estradiol between all doses of the estradiol matrix transdermal system and placebo in terms of the percentage change from baseline in the bone mineral density (BMD) of the L1-L4 anteroposterior lumbar spine (0.1 and 0.05 mg/d, P < 0.001; 0.0375 mg/d, P = 0.024; 0.025 mg/d, P = 0.002). Percentage changes from baseline in the BMD of the femoral neck after 2 years of treatment also consistently demonstrated the efficacy of the estradiol matrix transdermal system compared with placebo (all, P less than or equal to 0.014). The estradiol matrix transdermal system was well tolerated. Conclusion: The estradiol matrix transdermal system was effective in preventing postmenopausal bone loss at dosages of 0.025 to 0.1 mg/d, and had a safety profile consistent with the known effects of estrogen/progestin.