## **Core Concept**
Emergency contraception refers to the use of medications or devices to prevent pregnancy after unprotected sex or contraceptive failure. The primary goal is to either prevent ovulation or implantation of a fertilized egg. Commonly used drugs include progestins, estrogen-progestin combinations, and selective progesterone receptor modulators.

## **Why the Correct Answer is Right**
is a selective progesterone receptor modulator (SPRM) used for emergency contraception. and are progestins and estrogen-progestin combinations, respectively, utilized in emergency contraceptive regimens. On the other hand, is primarily an antiprotozoal and antimalarial drug. Its mechanism does not align with the pathways targeted for emergency contraception.

## **Why Each Wrong Option is Incorrect**
* **Option A:** is used in emergency contraception as it acts on the progesterone receptors, affecting ovulation and possibly implantation.
* **Option B:** is another drug employed for preventing pregnancy after unprotected sex, working through progestin receptors.
* **Option D:** is used as an emergency contraceptive pill, especially when given in a single dose or split dose, affecting hormonal balance.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that emergency contraception should be initiated as soon as possible after unprotected sex, ideally within 72 hours, for maximum efficacy. is not used for emergency contraception; instead, it's crucial for its antimalarial properties.

## **Correct Answer:** . Levonorgestrel