COMPARATIVE BIOAVAILABILITY STUDY OF A MATRIX VERSUS A RESERVOIR TRANSDERMAL ESTRADIOL PATCH IN HEALTHY POSTMENOPAUSAL WOMEN

The single-application bioavailability of estradiol from a new matrix (Climaderm(R)) versus a standard reservoir (Estraderm(R) TTS 50) trans dermal therapeutic system was investigated in a prospective, open-labe l, randomized, two-period crossover study in healthy postmenopausal vo lunteers. Each system was labeled to deliver approximately 0.05 mg of estradiol per day and was applied to the abdominal area and worn conti nuously for 4 days; there was a minimum 5-day washout between the two study periods. For each study period, venous blood samples were obtain ed before patch application, during treatment (20 samples), and after patch removal (3 samples) and assayed for estradiol and estrone. In ad dition, the samples obtained at 0, 8, 12, 24, 48, 72, 96, and 120 hour s after application were assayed for follicle-stimulating hormone (FSH ) and luteinizing hormone (LH). Twenty-six women completed both study periods, No differences between the patches were detected with regard to peak concentration and time to peak concentration. Based on area un der the curve, the two patches were bioequivalent through 48 hours. Fr om 48 to 96 hours, however, the matrix patch produced a more consisten t level of estradiol. Mean values for the levels of estradiol, estrone , FSH, and LH for the entire study period are presented.