Objective: To determine the efficacy and local tolerance of a new matrix transdermal drug-delivery system that delivers 0.02 mg of 17 beta-estradiol (E2) daily for 7 days for the relief of vasomotor symptoms.
Methods: A total of 324 surgically or naturally menopausal women, all with prior hysterectomy and moderate to severe vasomotor symptoms (56-140 hot flushes per week, with episodes of sweating, during a baseline observation period), participated in two independent, 12-week, randomized, double-blind, placebo-controlled studies. After a 4-week, treatment-free period, each woman received a continuous regimen of either one E2 transdermal system, two E2 transdermal systems, or placebo transdermal system(s) applied every week for 12 weeks. Efficacy was measured as reduction in hot flush frequency, determined from subject diaries. To measure local tolerance, skin irritation (erythema and edema) was objectively and systematically evaluated under blue light after removal of the transdermal system(s). Serum E2 and estrone concentrations were determined in one of the studies during baseline and on days 1, 9, 30, 58, 79, and 84.
Results: Mean hot flush frequency decreased from 80 hot flushes per week at baseline to approximately 13 hot flushes per week (84% decrease) after 12 weeks of transdermal E2 treatment. Compared with placebo, the decrease in hot flush frequency was significant as early as weeks 2 and 3, and was maintained through the end of the study. Few clinically significant skin reactions occurred, and only nine (3%) of the subjects withdrew because of a skin effect. After initial increase, serum E2 concentrations remained stable throughout the study, achieving values of approximately 20 and 40 pg/mL above baseline for one and two E2 transdermal systems, respectively.
Conclusion: The E2 transdermal system effectively reduced the frequency of moderate to severe vasomotor symptoms as early as the second week of therapy and was very well tolerated. The decrease in hot flush frequency was similar to that reported for oral and other transdermal estrogens, but at lower serum E2 concentrations. This result may be due to the stable E2 blood level achieved with this transdermal system.