Megestrol is a semi-synthetic derivative of progesterone with progesterone-like action (progestogen). If suppresses the secretion of gonadotropin-releasing hormones from the hypothalamus, respectively of gonadotropic hormones (follicle-stimulating and luteinizing) from the anterior pituitary gland, the maturation of the follicles and the ovulation. A condition similar to pregnancy is achieved, without the occurrence of estrus. It is active also for internal administration. The product has anti-estrogen, anti-ovulation and anti-fertility effects.