Corpus luteum is essential for establishing and maintaining pregnancy in females. The corpus luteum secretes progesterone, which is a steroid hormone responsible for the decidualization of the endometrium (its development) and maintenance, respectively. It also produces relaxin, a hormone responsible for softening of the pubic symphysis which helps in parturition. If the egg is not fertilized, the corpus luteum stops secreting progesterone and decays (after approximately 10 days in humans). It then degenerates into a corpus albicans, which is a mass of fibrous scar tissue. The uterine lining (endometrium) is expelled through the vagina (in mammals that go through a menstrual cycle).
Progesterone carboxymethyloxime potassium salt) showed water solubility that was increased by more than four orders of magnitude relative to progesterone (solubility = 9.44 mol/L and 0.0006 mol/L, respectively). In addition, it showed an "in vitro" terminal half-life in rat liver microsomes that was 363-fold longer than that of progesterone (half-life = 795.5 minutes and 2.2 minutes, respectively). As such, P4-3-CMO could have both improved absorption and increased metabolic stability relative to progesterone. However, the compound has not been further assessed nor studied in humans. Progesterone carboxymethyloxime Progesterone carboxymethyloxime, or progesterone 3-("O"-carboxymethyl)oxime (P4-3-CMO), is a progestin which was never marketed. It is an