Trimegestone-13C,d3 is 13C and deuterated labeled Trimegestone (HY-106827). Trimegestone (RU 27987) is an orally active 19-norpregnane progestin. Trimegestone binds to progesterone receptor (PR) with an IC50 value of 3.3 nM (rat PR). Trimegestone increases alkaline phosphatase activity (EC50=0.1 nM) but not luciferase activity. Trimegestone also shows a weak antiandrogenic activity (weak androgen receptor affinity). Trimegestone can be used in studies of contraception or menopausal syndromes[1][2].