Norethindrone and Mestranol Tablets
»Norethindrone and Mestranol Tablets contain not less than 90.0percent and not more than 110.0percent of the labeled amount of norethindrone (C20H26O2),and not less than 90.0percent and not more than 110.0percent of the labeled amount of mestranol (C21H26O2).
Packaging and storage— Preserve in well-closed containers.
Identification— Crush 1Tablet in 1mLof alcohol in a 15-mLconical centrifuge tube,and centrifuge briefly.Apply 10µLof this test solution and 10µLeach of solutions containing,respectively,about 1mg per mLof USP Norethindrone RSin alcohol and about 50µg per mLof USP Mestranol RSin alcohol at equidistant points along a line about 2.5cm from the bottom of a thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel and previously activated by heating at 105for 30minutes.Develop the chromatogram in a mixture of equal volumes of ethyl acetate and cyclohexane in a suitable chamber,previously equilibrated with the solvent mixture,until the solvent front has moved about three-fourths of the length of the plate.Remove the plate,air-dry,and observe under short-wavelength UVlight:the principal spot from the test solution appears at the same RFvalue as the principal spot from USP Norethindrone RS,at about RF0.6.Spray the plate with a sulfuric acid and methanol mixture prepared by cautiously adding and mixing sulfuric acid in small increments to 30mLof chilled anhydrous methanol in a 100-mLvolumetric flask.Adjust to room temperature,dilute with sulfuric acid to volume,and mix.Heat the plate at 105for 10minutes:the pink spot from the test solution appears at the same RFvalue as the pink spot from USP Mestranol RS(about RF0.8).
Dissolution á711ñ— [NOTE—Exercise care in filtering solutions containing mestranol to prevent adsorptive loss of the drug.Centrifugation may be used instead of filtration with nonadsorptive membrane filters.Withdraw dissolution aliquots with glass or polytef pipets or syringes that have been checked for adsorptive loss.Use glass dissolution vessels and polytef-coated or solid polytef paddles.]
Medium: 0.09%sodium lauryl sulfate in 0.1Nhydrochloric acid;500mL.
Apparatus 2: 75rpm.
Time: 60minutes.
Determine the amounts of norethindrone (C20H26O2)and mestranol (C21H26O2)dissolved,employing the following method.
Mobile phase— Prepare a degassed and filtered mixture of water and acetonitrile (60:40).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).
Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 205-nm detector and a 4.6-mm ×25-cm column that contains packing L10.The flow rate is about 1mLper minute.Chromatograph replicate injections of a filtered portion of a Standard solution of USP Norethindrone RSand USP Mestranol RSin Dissolution Mediumhaving known concentrations similar to those expected in the solution under test,and record the peak responses as directed for Procedure:the relative standard deviation is not more than 3.0%.The minimum number of theoretical plates for the mestranol peak is 4000,and the tailing factors for the norethindrone and mestranol peaks do not exceed 1.5.
Procedure— Separately inject equal volumes (about 200µL)of the Standard solution and a filtered portion of the solution under test into the chromatograph,record the chromatograms,and measure the responses for the major peaks.The relative retention times are about 0.4for norethindrone and 1.0for mestranol.Calculate the quantities of norethindrone and mestranol dissolved by comparison of the corresponding peak responses obtained from the Standard solution and the test solutions.
Tolerances— Not less than 75%(Q)of the labeled amount of C20H26O2and 75%(Q)of the labeled amount of C21H26O2are dissolved in 60minutes.
Uniformity of dosage units á905ñ: meet the requirements for Content Uniformitywith respect to norethindrone and to mestranol.
Assay—
Mobile phase— Prepare a filtered and degassed mixture of acetonitrile and water (50:50).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).
Internal standard solution— Transfer about 80mg of progesterone into a 100-mLvolumetric flask,add 50mLof acetonitrile,dilute with water to volume,and mix.
Mestranol standard stock solution— Dissolve an accurately weighed quantity of USP Mestranol RSin acetonitrile,and dilute quantitatively and stepwise with acetonitrile to obtain a solution having a known concentration of about 0.05mg per mL.
Norethindrone standard stock solution— Using an accurately weighed quantity of USP Norethindrone RS,prepare a solution in acetonitrile having a known concentration of about 1mg per mL.
Standard preparation— Transfer 2.0mLof Internal standard solutioninto a 100-mLvolumetric flask.Add accurately measured volumes of Mestranol standard stock solutionand Norethindrone standard stock solutionso that the final known concentrations,in mg per mL,of the Reference Standards correspond numerically to about one-fiftieth of the labeled amounts of the corresponding ingredients in the Tablets.Add 50mLof water,dilute with acetonitrile to volume,and mix.
Assay preparation— Transfer 10Tablets to a 250-mLvolumetric flask,add 50mLof water,and shake by mechanical means until the Tablets are completely disintegrated.Add 10.0mLof Internal standard solutionand 165mLof acetonitrile,and mix.Sonicate for about 2minutes.Dilute with acetonitrile to volume,and mix.Allow solid particles to settle,or centrifuge if necessary,to obtain a slightly turbid solution.Transfer 5.0mLof this solution to a 10-mLvolumetric flask,add 1.0mLof acetonitrile,dilute with water to volume,and mix.
Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 200-nm detector and a 4.6-mm ×15-cm column that contains packing L7.The flow rate is about 1.0mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the column efficiency determined from the mestranol peak is not less than 6000theoretical plates,the resolution,R,between the progesterone and mestranol peaks is not less than 5.0,and the relative standard deviation for six replicate injections is not more than 2.0%(both peaks).
Procedure— Separately inject equal volumes (about 25µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.The relative retention times are about 2.5for mestranol and 1.0for norethindrone.Calculate the quantities,in mg,of norethindrone (C20H26O2)and mestranol (C21H26O2)in each Tablet taken by the formula:
50C(RU/RS),
in which Cis the concentration,in mg per mL,of the appropriate USP Reference Standard in the Standard preparation,and RUand RSare the peak response ratios,at corresponding retention times,obtained from the Assay preparationand the Standard preparation,respectively.
Auxiliary Information— Staff Liaison:Clydewyn M.Anthony,Ph.D.,Scientist
Expert Committee:(PA1)Pharmaceutical Analysis 1
USP28–NF23Page 1395
Phone Number:1-301-816-8139