ATC code: G03AD02 The most recent approval by FDA is Ulipristal Acetate, approved on August 13th 2010 under the trade name Ella. Ulipristal Acetate (previously known by the research code CDB-2914 or VA-2914) is a progesterone agonist/antagonist emergency contraceptive, indicated for prevention of pregnancy following unprotected intercourse or known or suspected contraceptive failure. This drug is a selective progesterone receptor modulator (SPRM) with antagonist and partial agonist effects (a progesterone agonist/antagonist) at the progesterone receptor (PR, NR3C3) (Uniprot code: P06401 ). The Progesterone Receptor is a member of a very significant family of proteins for drug discovery, the Nuclear Receptors , a family of around 50 genes which are transcription factors , the transcription by NRs is usually ligand regulated. Ulipristal Acetate prevents progesterone, the endogenous ligand, from occupying its receptor. Ulpristal Acetate binds in the ligand binding domain (LBD) of PR