Which medication blocks progesterone receptors to terminate a pregnancy?

Which medication blocks progesterone receptors to terminate a pregnancy?

• A. Leuprolide
• B. Mifepristone
• C. Misoprostol
• D. Zidovudine

Answer: (B)

Blocking progesterone action is what allows certain medical abortions to occur. Mifepristone acts as an antiprogestin by binding to progesterone receptors with high affinity, preventing progesterone from signaling. Without that progesterone support, the decidual lining breaks down and the endometrium can no longer sustain the pregnancy, leading to detachment and bleeding. This mechanism is why mifepristone is used for medical abortion, typically followed by misoprostol to induce uterine contractions and complete the process, especially in early gestation (roughly up to 70 days). Other drugs in the mix do not block progesterone receptors: leuprolide suppresses gonadotropin release to lower hormone production, misoprostol stimulates uterine contractions, and zidovudine is an antiviral with no role in terminating pregnancy.

Blocking progesterone action is what allows certain medical abortions to occur. Mifepristone acts as an antiprogestin by binding to progesterone receptors with high affinity, preventing progesterone from signaling. Without that progesterone support, the decidual lining breaks down and the endometrium can no longer sustain the pregnancy, leading to detachment and bleeding. This mechanism is why mifepristone is used for medical abortion, typically followed by misoprostol to induce uterine contractions and complete the process, especially in early gestation (roughly up to 70 days). Other drugs in the mix do not block progesterone receptors: leuprolide suppresses gonadotropin release to lower hormone production, misoprostol stimulates uterine contractions, and zidovudine is an antiviral with no role in terminating pregnancy.