Levonorgestrel

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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Levonorgestrel contains not less than 98.0 percent and not more than 102.0 percent of C₂₁H₂₈O₂, calculated on the dried basis.

Packaging and storage—Preserve in well-closed, light-resistant containers.

USP Reference standards 〈11〉

USP Levonorgestrel RS

1 Identification

Change to read:

A: Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197K (CN 1-May-2020)

B: Meeting the requirements of the tests for Specific rotation and Melting range provides identification distinguishing it from norgestrel.

Melting range 〈741〉: between 232° and 239°, but the range between beginning and end of melting does not exceed 4°.

Specific rotation 〈781S〉: between −30° and −35°.

Test solution: 20 mg per mL, in chloroform.

Loss on drying 〈731〉—Dry it at 105° for 5 hours: it loses not more than 0.5% of its weight.

Residue on ignition 〈281〉: not more than 0.3%.

Limit of ethynyl group—Dissolve 200 mg in about 40 mL of tetrahydrofuran. Add 10 mL of silver nitrate solution (1 in 10), and titrate with 0.1 N sodium hydroxide VS, using either a glass-calomel or a silver-silver chloride electrode system with potassium nitrate filling solution. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N sodium hydroxide is equivalent to 2.503 mg of ethynyl group (-C≡CH). Not less than 7.81% and not more than 8.18% of ethynyl group is found.

Chromatographic purity—Proceed as directed in the test for Chromatographic purity under Norgestrel, using USP Levonorgestrel RS in place of USP Norgestrel RS. The requirements of the test are met if the sum of the impurities in the Test preparation does not exceed 2.0% and no single impurity is greater than 0.5%.

2 Assay

Using USP Levonorgestrel RS, proceed as directed in the Assay under Norgestrel, except to read “Levonorgestrel” in place of “Norgestrel.”