What is used as Emergency contraceptive?
**Core Concept**
Emergency contraception refers to the use of medications or devices to prevent pregnancy after unprotected sex or contraceptive failure. It works by preventing or delaying ovulation, fertilization, or implantation of a fertilized egg.
**Why the Correct Answer is Right**
The most effective emergency contraceptive is **levonorgestrel**, a progestin-only hormonal contraceptive. It works by inhibiting ovulation, thickening cervical mucus to prevent sperm penetration, and altering the uterine environment to prevent implantation. Levonorgestrel is available over-the-counter in many countries and can be effective up to 72 hours after unprotected sex.
**Why Each Wrong Option is Incorrect**
**Option A:** **Urea** is a waste product and not used as an emergency contraceptive.
**Option B:** **Mifepristone** is an antiprogestin used in medical abortion, not emergency contraception.
**Option C:** **Metformin** is a medication for type 2 diabetes and has no role in emergency contraception.
**Clinical Pearl / High-Yield Fact**
Emergency contraception is most effective when used within 24 hours of unprotected sex. The Yuzpe regimen, which combines estrogen and progestin, is less effective and has more side effects than levonorgestrel.
**Correct Answer:** B. Mifepristone is an antiprogestin used in medical abortion, not emergency contraception.