According to WHO, what is the dose of LNG?

NORCET 2 - 2021 (shift-1)

Pharmacology

Easy

Appeared in: NORCET 2 - 2021 (shift-1)

Explanation

The World Health Organization (WHO) and other major health bodies recommend a single dose of 1.5 mg of Levonorgestrel (LNG) for emergency contraception.
This regimen is effective when taken as soon as possible after unprotected intercourse, ideally within 72 hours, with some efficacy up to 120 hours.
The primary mechanism of action is the prevention or delay of ovulation; it does not interrupt an established pregnancy.
This single-dose regimen has replaced the older two-dose regimen (0.75 mg taken 12 hours apart) due to similar efficacy and better compliance.

Option B: The unit 'mcg' (microgram) is 1/1000th of a milligram ('mg'). A dose of 1.5 mcg is therapeutically insignificant and 1000 times too low to be effective for emergency contraception.
Option C: A 3 mg dose is double the standard WHO-recommended dose. Increasing the dose does not improve efficacy and is likely to increase the incidence and severity of side effects like nausea and headache.
Option D: The unit 'IU' (International Unit) is a measure of biological activity, not mass. It is used for substances like vitamins, insulin, and vaccines. Synthetic hormones like levonorgestrel are dosed by mass (milligrams or micrograms).

Clinical Relevance

Nursing practice connection: Knowing Pharmacology: WHO recommended dosage of Levonorgestrel (LNG) for emergency contraception helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses play a vital role in counseling patients on the correct use of emergency contraception, emphasizing that it is not a regular method of birth control and does not protect against STIs.
Accurate patient education on timing is critical for effectiveness. A nurse must clearly state that the pill should be taken 'as soon as possible' to maximize the chance of preventing pregnancy.
A key safety point is advising patients to seek medical advice or take another pill if they vomit within two hours of taking the medication, as the dose may not have been absorbed.

How to Approach the Question

First, identify the key components of the question: the drug (LNG), the authority (WHO), and the specific information required (dose).
Recognize this as a factual recall question from pharmacology.
Carefully examine the options, paying close attention to both the numerical value and the unit of measurement (mg, mcg, IU). This is a common way questions test for detail and safety knowledge.
Eliminate options with incorrect units. 'IU' is a measure of biological activity, not mass, so it's incorrect for LNG. 'mcg' is a much smaller unit than 'mg', and 1.5 mcg would be an extremely low dose.
Between the remaining options with the correct unit (mg), recall the standard WHO-recommended dose for single-dose emergency contraception.
Select 1.5 mg as the standard, evidence-based dose, and recognize 3 mg as an incorrect, non-standard dose.

Concept Tested & Keywords

Concept Tested: Pharmacology: WHO recommended dosage of Levonorgestrel (LNG) for emergency contraception.
Stem keywords: WHO, dose, LNG
Lead-in keywords: what is

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