Final answer:
The MOA of Mifepristone is to block progesterone, leading to the breakdown of the endometrium, while Misoprostol causes uterine contractions to expel the embryo. For an ectopic pregnancy, Methotrexate is used to inhibit cell division and stop the growth of embryonic cells.
Step-by-step explanation:
Medications for Pregnancy Termination: Mifepristone & Misoprostol
The mechanism of action (MOA) for Mifepristone is that it is an antiprogestogen, which means it inhibits the action of progesterone, a hormone crucial for the continuation of pregnancy. Mifepristone induces the endometrium (the lining of the uterus) to break down, leading to the detachment of the embryo. Misoprostol, which is often used in conjunction with Mifepristone, is a prostaglandin. It works by causing the uterus to contract and expel the embryo and the endometrium.
In the case of an ectopic pregnancy, where the embryo implants outside the uterus, usually in the fallopian tube, a different medication called Methotrexate is typically used. Methotrexate is a folic acid antagonist that inhibits cell division, thus stopping the growth of the embryonic cells in the ectopic pregnancy and allowing the body to absorb the tissue.