A randomized controlled trial of four doses of transdermal estradiol for preventing postmenopausal bone loss....

To determine the effects of four doses of a 7-day transdermal 17beta-estradiol (E2) delivery system, including 0.025 mg/day, on bone loss in postmenopausal women.

This was a multicenter, double-masked, randomized, placebo-controlled study of the effects of transdermal E2 at doses of 0.025, 0.05, 0.06, and 0.1 mg/day for the prevention of postmenopausal osteoporosis. Efficacy was evaluated from bone mineral density of lumbar vertebrae L2-L4, radius, proximal femur, and total hip measured with dual-energy x-ray absorptiometry. Serum osteocalcin and urinary pyridinoline and deoxypyridinoline concentrations were measured.

At 24 months, E2 doses of 0.025, 0.05, 0.06, and 0.1 mg/day resulted in mean increases in bone mineral density of the lumbar spine of 2.37%, 4.09%, 3.28%, and 4.70%, respectively, and increased bone mineral density of the total hip by 0.26%, 2.85%, 3.05%, and 2.03%, respectively. All increases were statistically significantly greater than placebo, which decreased bone mineral density by 2.49% at the spine and 2.04% at the hip. Consistent and significant improvements in biochemical markers of bone turnover also were noted at various intervals in all treatment groups. The most frequent adverse events were local reactions from the transdermal drug-delivery system, effects of estrogen, and menopausal symptoms.

Transdermal E2 at doses of 0.025, 0.05, 0.06, and 0.1 mg/day effectively prevented bone loss in postmenopausal women.