Steady‐State Pharmacokinetics Following Application of a Novel Transdermal Estradiol Spray in Healthy Postmenopausal Women

Abstract

This study was designed to evaluate the steady-state pharmacokinetics (PK) of estradiol and its metabolites, estrone and estrone sulfate, following application of a novel estradiol transdermal spray to healthy postmenopausal women. Participants were randomly assigned in parallel to receive 1-, 2-, or 3-spray doses (24 participants/dose level) of a 1.7% estradiol metered-dose transdermal spray (1.53 mg/spray) once daily for 14 days. Blood was collected predose on days 1 to 14 and over 7 days after the last dose. Serum concentrations for all 3 analytes reached steady state by day 7 or 8 and were still slightly above baseline on day 21. Estradiol, estrone, and estrone sulfate serum concentrations generally increased with increasing dose. Mean estradiol and estrone maximum serum concentration (C(max)) following 1, 2, or 3 sprays for 14 days were 36 and 50, 57 and 60, and 54 and 71 pg/mL, respectively. Estradiol time when maximum concentration occurred (t(max)) was 18 to 20 hours. The area under the serum concentration-time curve over 24 hours following the last dose of study drug (AUC(0-24 h)) on day 14 for the 1-, 2-, and 3-spray groups, respectively, was 471, 736, and 742 pg.h/mL for estradiol; 886, 1208, and 1367 pg x h/mL for estrone; and 16,501, 26,515, and 27,971 pg x h/mL for estrone sulfate. The metered-dose estradiol transdermal spray delivers estradiol at therapeutic levels and produces low serum estrone concentrations.