(lee'' voe nor jes' trel).
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C21H28O2 312.45

18,19-Dinorpregn-4-en-20-yn-3-one, 13-ethyl-17-hydroxy-, (17)-()-.
()-13-Ethyl-17-hydroxy-18,19-dinor-17-pregn-4-en-20-yn-3-one [797-63-7].
» 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 Click to View Structure
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 (-CCH). 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%.
Assay— Using USP Levonorgestrel RS, proceed as directed in the Assay under Norgestrel, except to read “Levonorgestrel” in place of “Norgestrel.”
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Mary S. Waddell
Scientific Liaison
(SM42010) Monographs - Small Molecules 4
Reference Standards RS Technical Services
USP35–NF30 Page 3674
Pharmacopeial Forum: Volume No. 34(3) Page 620