Objective: To study the effect of high doses of estradiol released from vaginal rings on the pharmacokinetics of hormones, and the long-term effect on hormones and hemostasis in postmenopausal women.
Design: A pilot, nonrandomized study.
Setting: Healthy volunteers in an academic research environment.
Patients: Postmenopausal women. Eight women were treated with 17 beta-estradiol from three vaginal rings, releasing 7.5 micro g per ring for a total of 22.5 micro g over 24 hours. The rings were changed every morning for 14 days.
Main outcome measure(s): Hemostatic changes were recorded.
Result(s): Estradiol was rapidly absorbed, and statistically significant increases in the levels were found after 15 minutes; C(max) was obtained after 1 hour and a steady state after 24 hours. No statistically significant changes were found in the levels of coagulation factors V, von Willebrand factor, and activated factor VII; nor were any changes observed for activated protein C resistance, coagulation inhibitors protein C, protein S, or plasminogen activator inhibitor-1. No indication of increased thrombin formation was demonstrated by analyses of prothrombin fragment 1+2, fibrin D-dimer, and soluble fibrin. CONCLUSION(S)No statistically significant changes in hemostasis were observed from the vaginal administration of estradiol using a dose equivalent to transdermal administration with a release rate of 100 micro g per 24 hours.