**Question:** Which is not an emergency contraceptive:

A. Plan B
B. Norlevo
C. Implanon
D. Depo-Provera

**Core Concept:** Emergency contraceptives are medications used to prevent pregnancy when used within a short timeframe after unprotected sexual intercourse or contraceptive failure. They primarily work by inhibiting ovulation or by increasing the cervical mucus consistency, making it difficult for sperm to reach the uterus.

**Why the Correct Answer is Right:** Depo-Provera (medroxyprogesterone acetate) is a progestin contraceptive hormone used for long-term contraception and does not fit the criteria for emergency contraception. It is typically administered as an intramuscular injection every 12 weeks and provides hormonal contraception rather than acting within a short timeframe after unprotected sex.

**Why Each Wrong Option is Incorrect:**

A. Plan B (levonorgestrel) and Norlevo (levonorgestrel and ethinylestradiol) are progestins that, when taken shortly after unprotected sex, can inhibit ovulation and increase cervical mucus consistency. They are commonly known as "morning-after pills" and can be taken over-the-counter without a prescription, making them suitable for emergency contraception.

B. Implanon (etonogestrel) is an implanted contraceptive device that delivers progestin hormones directly into the bloodstream. It is a long-term contraceptive method and not suitable for emergency contraception.

**Clinical Pearl:** Emergency contraceptives should be prescribed or purchased immediately available over-the-counter without a prescription to ensure prompt access and use after unprotected sex or contraceptive failure.

**Core Concept:** Emergency contraceptives are designed to act within a short timeframe after unprotected sex, while long-term contraceptives like Depo-Provera are administered periodically and do not meet the criteria for emergency contraception.