Han S, Cho YS, Yoon SK, et al. - Researchers conducted this first-in-human, multi-center, phase 1, randomized, double-blind, placebo-controlled, single-dose ascending trial examining the safety, tolerability, pharmacokinetics, and pharmacodynamics of TU2670, a novel orally active, non-peptide GnRH antagonist administered to healthy female individuals. They randomized 16 healthy premenopausal women (23 to 45 years of age) to receive 20, 40, 80, and 160 mg TU2670 (GnRH antagonist) or placebo 7 days (±1 day) after the onset of menstrual bleeding. Healthy premenopausal women well tolerated the single administration of TU2670 and showed the dose-dependent suppression of LH, FSH, and estradiol, indicating rapid and significant inhibition of pituitary and ovarian hormones.