17-Hydroxy-19-nor-17a-pregn-4-en-20-yn-3-one acetate [51-98-9].
»Norethindrone Acetate contains not less than 97.0percent and not more than 103.0percent of C22H28O3,calculated on the dried basis.
Packaging and storage Preserve in well-closed containers.
Completeness of solution The solution prepared for the determination of Specific rotationis clear and free from undissolved solids.
Identification, Infrared Absorption á197Kñ.
Specific rotation á781Sñ: between 32and 38.
Test solution: 20mg per mL,in dioxane.
Loss on drying á731ñ Dry it at 105for 3hours:it loses not more than 0.5%of its weight.
Limit of ethynyl group Proceed as directed in the test for Ethynyl groupunder Norethindrone.Not less than 7.13%and not more than 7.57%of ethynyl group is found.
Adsorbent: 0.25-mm layer of chromatographic silica gel mixture.
Test solution Prepare a solution of Norethindrone Acetate in chloroform having a concentration of 10mg per mL.
Standard stock solution Prepare a solution of USP Norethindrone Acetate RSin chloroform having a known concentration of 10mg per mL.
Standard solutions Dilute accurately measured volumes of the Standard stock solutionwith chloroform to obtain Standard solutions A,B,C,and Dhaving known concentrations of 150µg per mL,50µg per mL,30µg per mL,and 10µg per mL,respectively.
Application volume: 10µL,as two 5-µLportions.
Developing solvent system: a mixture of toluene and ethyl acetate (1:1).
Procedure Proceed as directed for Thin-Layer Chromatographyunder Chromatography á621ñ,except to apply the solutions along a line 2.5cm from the edge of the plate.Spray the plate with a mixture of methanol and sulfuric acid (7:3),and heat at 100for 5minutes.The Test solutionexhibits a principal spot at the same RFvalue as the principal spot of Standard solution A.Any individual secondary spot is not more intense than the spot in the chromatogram obtained from Standard solution B:not more than 0.5%of any individual impurity is found.The sum of the intensities of all of the secondary spots is not more intense than the spot in the chromatogram obtained from Standard solution A:not more than 1.5%of total impurities is found.
Mobile phase Prepare a filtered and degassed mixture of acetonitrile and water (6:4).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).
Resolution solution Dissolve accurately weighed quantities of desoxycorticosterone acetate and USP Norethindrone Acetate RSin Mobile phaseto obtain a solution having concentrations of about 80µg of each per mL.
Test solution Transfer about 62.5mg of Norethindrone Acetate,accurately weighed,to a 25-mLvolumetric flask,dissolve in and dilute with Mobile phaseto volume,and mix.
Diluted test solution Transfer 1.0mLof the Test solutionto a 100-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.
Chromatographic system (see Chromatography á621ñ) The liquid chromatograph is equipped with a 254-nm detector and a 4.6-mm ×25-cm column that contains packing L1.The flow rate is about 1mLper minute.Chromatograph the Resolution solution,and record the peak responses as directed for Procedure:the relative retention times are about 0.83for desoxycorticosterone acetate and 1.0for norethindrone acetate;and the resolution,R,between desoxycorticosterone acetate and norethindrone acetate is not less than 3.5.
Procedure Separately inject equal volumes (about 20µL)of the Diluted test solutionand the Test solutioninto the chromatograph,record the chromatograms for twice the retention time of norethindrone acetate,and measure all of the peak areas.Calculate the percentage of each impurity in the portion of Norethindrone Acetate taken by the formula:
ri/rs,in which riis the peak area for each impurity obtained from the Test solution;and rsis the sum of all the peaks obtained from the Diluted test solution.[NOTEExclude any peak having a response that is less than 0.025%of the norethindrone acetate peak response obtained from the Test solution.]Not more than 0.5%of any individual impurity is found;and not more than 1.0%of total impurities is found.
Organic volatile impurities,Method IVá467ñ: meets the requirements.
Assay Transfer about 100mg of Norethindrone Acetate,accurately weighed,to a 200-mLvolumetric flask,add alcohol to volume,and mix.Transfer 5.0mLof this solution to a 250-mLvolumetric flask,dilute with alcohol to volume,and mix.Dissolve an accurately weighed quantity of USP Norethindrone Acetate RSin alcohol,and dilute quantitatively and stepwise with alcohol to obtain a Standard solution having a known concentration of about 10µg per mL.Concomitantly determine the absorbances of both solutions in 1-cm cells at the wavelength of maximum absorbance at about 240nm,with a suitable spectrophotometer,using alcohol as the blank.Calculate the quantity,in mg,of C22H28O3in the portion of Norethindrone Acetate taken by the formula:
10C(AU/AS),in which Cis the concentration,in µg per mL,of USP Norethindrone Acetate RSin the Standard solution,and AUand ASare the absorbances of the solution of Norethindrone Acetate and the Standard solution,respectively.
Auxiliary Information Staff Liaison:Clydewyn M.Anthony,Ph.D.,Scientist
Expert Committee:(PA1)Pharmaceutical Analysis 1
USP28NF23Page 1396Pharmacopeial Forum:Volume No.27(4)Page 2762