Naproxen Sodium
C14H13NaO3 252.24

2-Naphthaleneacetic acid,6-methoxy-a-methyl-,sodium salt,(S)-.
(-)-Sodium (S)-6-methoxy-a-methyl-2-naphthaleneacetate [26159-34-2].
»Naproxen Sodium contains not less than 98.0percent and not more than 102.0percent of C14H13NaO3,calculated on the dried basis.
Packaging and storage— Preserve in tight containers.
Identification—
A: Infrared Absorption á197Kñ.
Solution: 25µg per mL.
Medium: methanol.
Absorptivities at 272nm,calculated on the dried basis,do not differ by more than 3%.
Specific rotation á781Sñ: between -15.3and -17.0.
Test solution: 50mg per mL,in 0.1Nsodium hydroxide.
Loss on drying á731ñ— Dry it in vacuum at 105for 3hours:it loses not more than 1.0%of its weight.
Heavy metals,Method Iá231ñ— Dissolve 1.0g in 20mLof water in a separator,add 5mLof 1Nhydrochloric acid,and extract with successive 20-mL,20-mL,and 10-mLportions of methylene chloride.Discard the methylene chloride extracts,and use the aqueous layer for the test:the limit is 0.002%.
Free naproxen— Dissolve about 5.0g in 25mLof water in a separator,and extract the solution with three 15-mLportions of chloroform.Evaporate the combined extracts on a steam bath to dryness.Dissolve the residue in 10mLof a mixture of methanol and water (3:1)previously neutralized with 0.1Nsodium hydroxide to the phenolphthalein endpoint.Add phenolphthalein TS,and titrate with 0.10Nsodium hydroxide:not more than 2.2mLis consumed (1.0%).
Chromatographic purity— Dissolve 100mg in 5mLof methanol.Dissolve a suitable quantity of USP Naproxen Sodium RSin methanol to obtain a Standard solutionhaving a known concentration of about 20mg per mL.Dilute a portion of this solution quantitatively with methanol to obtain three Comparison solutionshaving concentrations of 20,60,and 100µg per mL(0.1%,0.3%,and 0.5%of the Standard solution),respectively.Apply separate 10-µLportions of the five solutions on the starting line to a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel mixture.Develop the chromatogram in a solvent system consisting of a mixture of toluene,tetrahydrofuran,and glacial acetic acid (30:3:1)until the solvent front has moved about three-fourths of the length of the plate.Remove the plate from the chamber,mark the solvent front,air-dry,and view under short-wavelength UVlight:the RFvalue of the principal spot in the chromatogram of the solution under test corresponds to that of the Standard solution,the intensity of any individual secondary spot does not exceed that of the 100-µg-per-mLComparison solution(0.5%),and the sum of the intensities of any secondary spots,similarly compared,does not exceed 2.0%.
Organic volatile impurities,Method Iá467ñ: meets the requirements.
Assay— Dissolve about 200mg of Naproxen Sodium,accurately weighed,in 50mLof glacial acetic acid containing 2drops of p-naphtholbenzein TSpreviously neutralized with 0.1Nperchloric acid if necessary.Titrate with 0.1Nperchloric acid VS.Each mLof 0.1Nperchloric acid is equivalent to 25.22mg of C14H13NaO3.
Auxiliary Information— Staff Liaison:Clydewyn M.Anthony,Ph.D.,Scientist
Expert Committee:(PA2)Pharmaceutical Analysis 2
USP28–NF23Page 1337
Phone Number:1-301-816-8139