For emergency contraception, a single tab of 0.75 mg of LNG was taken, it should be followed by which of the following?
**Core Concept**
Emergency contraception with levonorgestrel (LNG) is a hormone-based method used to prevent pregnancy after unprotected sex or contraceptive failure. LNG works by inhibiting or delaying ovulation, and its efficacy is increased when taken with a backup method of contraception.
**Why the Correct Answer is Right**
The correct answer is a second tab of LNG, taken 12 hours after the initial dose. This is because LNG has a biphasic effect on ovulation, with the initial dose causing a delay and the second dose causing an inhibition of ovulation. The second dose is crucial in enhancing the contraceptive efficacy of LNG, especially in women who have not yet ovulated after the initial dose. The 12-hour interval allows for the maximum absorption of LNG and its subsequent effect on the hypothalamic-pituitary-gonadal axis.
**Why Each Wrong Option is Incorrect**
* **Option A:** This is incorrect because it does not specify the correct timing and dose of LNG. Taking a single dose without a backup is not sufficient for effective emergency contraception.
* **Option B:** This is incorrect because there is no evidence to support the use of a progestin-only pill (POP) as a backup method for emergency contraception with LNG.
* **Option C:** This is incorrect because it does not specify the correct timing and dose of LNG. Taking a second dose without waiting 12 hours may reduce the efficacy of emergency contraception.
**Clinical Pearl / High-Yield Fact**
To remember the correct timing of LNG for emergency contraception, use the mnemonic "LNG-12": Levonorgestrel (LNG) taken at 12 hours.
**Correct Answer:** C.