Norethindrone and Ethinyl Estradiol Tablets
» Norethindrone and Ethinyl Estradiol Tablets contain not less than 90.0 percent and not more than 110.0 percent of the labeled amount of norethindrone (C20H26O2), and not less than 90.0 percent and not more than 110.0 percent of the labeled amount of ethinyl estradiol (C20H24O2).
Packaging and storage Preserve in well-closed containers.
USP Reference standards 11
Identification Crush 1 Tablet in 1 mL of alcohol in a 15-mL conical centrifuge tube, and warm to 50 for 10 minutes with gentle swirling. Cool, and centrifuge to obtain a clear solution. Apply 20 µL of this test solution and 20 µL of an alcohol solution containing, in each mL, about 1 mg of USP Norethindrone RS and about 50 µg of USP Ethinyl Estradiol RS at equidistant points along a line about 2.5 cm from the bottom of a thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel and previously activated by heating at 105 for 30 minutes. Develop the chromatogram in a mixture of toluene and ethyl acetate (4:1) in a suitable chamber, previously equilibrated with the solvent mixture, until the solvent front has moved about 10 cm. Remove the plate, and air-dry. Spray the plate with sulfuric acidmethanol, prepared by cautiously adding 70 mL of sulfuric acid in small increments to 30 mL of methanol chilled in an ice-bath, and mixing: the spots from the test solution have the same RF values as the spots from USP Ethinyl Estradiol RS and from USP Norethindrone RS.
Dissolution 711 [noteExercise care in filtering and handling solutions containing ethinyl estradiol 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 dodecyl sulfate in 0.1 N hydrochloric acid; 500 mL.
Apparatus 2: 75 rpm.
Time: 60 minutes.
Determine the amounts of norethindrone (C20H26O2) and ethinyl estradiol (C20H24O2) dissolved, employing the following method.
Mobile phase Prepare a degassed and filtered mixture of 0.02 M pH 6.0 phosphate buffer and acetonitrile (65:35). Make adjustments if necessary (see System Suitability under Chromatography 621).
Chromatographic system (see Chromatography 621)The liquid chromatograph is equipped with a 200-nm detector, and a 5-mm × 8.3-cm column that contains 3-µm packing L1. The flow rate is about 1 mL per minute. Chromatograph replicate injections of a filtered portion of a Standard solution of USP Norethindrone RS and USP Ethinyl Estradiol RS in Dissolution Medium having concentrations similar to those expected in the solution under test. [noteA volume of methanol not exceeding 4% of the total final volume of the Standard solution may be used in preparing the Standard solution. ] Record the peak responses as directed for Procedure: the resolution, R, for norethindrone and ethinyl estradiol is not less than 1.5; the minimum number of theoretical plates for the ethinyl estradiol peak is not less than 7000; the tailing factor does not exceed 2.0 for either peak; and the relative standard deviation is not more than 3.0%.
Procedure Separately inject equal volumes (about 100 µL) 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 0.9 for norethindrone and 1.0 for ethinyl estradiol. Calculate the quantities of norethindrone (C20H26O2) and ethinyl estradiol (C20H24O2) dissolved by comparison of the corresponding peak responses obtained from the Standard solution and the solution under test.
Tolerances Not less than 75% (Q) of each of the labeled amounts of C20H26O2 and C20H24O2, respectively, are dissolved in 60 minutes.
Uniformity of dosage units 905: meet the requirements for Content Uniformity with respect to norethindrone and to ethinyl estradiol.
Mobile phase Prepare a filtered and degassed mixture of acetonitrile and water (60:40). Make adjustments if necessary (see System Suitability under Chromatography 621).
Internal standard solution Transfer about 15 mg of valerophenone into a 250-mL volumetric flask, add 125 mL of acetonitrile, dilute with water to volume, and mix.
Ethinyl estradiol standard stock solution Dissolve an accurately weighed quantity of USP Ethinyl Estradiol RS in acetonitrile, and dilute quantitatively and stepwise with acetonitrile to obtain a solution having a known concentration of about 0.09 mg 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 1.25 mg per mL.
Mixed standard preparation Transfer 5.0 mL of Internal standard solution into a 100-mL volumetric flask. Add accurately measured volumes of Ethinyl estradiol standard stock solution and Norethindrone standard stock solution so that the final known concentrations, in mg per mL, of the Reference Standards correspond numerically to about one-twentieth of the labeled amounts of the corresponding ingredients in the Tablets. Add (26 X) mL of acetonitrile, X being the total volume of the standard stock solution taken. Dilute with a mixture of acetonitrile and water (45 in 100) to volume, and mix.
Assay preparation Transfer 10 Tablets to a 100-mL volumetric flask, add 20 mL of water, and shake by mechanical means until the tablets are completely disintegrated. Add 10.0 mL of Internal standard solution and 60 mL of acetonitrile, and mix. Sonicate for about 2 minutes. Dilute with acetonitrile to volume, and mix. Allow solid particles to settle, or centrifuge if necessary to obtain a slightly turbid solution. Dilute 5.0 mL of this solution with a mixture of acetonitrile and water (45 in 100) to 10.0 mL, and mix.
Chromatographic system (see Chromatography 621)The liquid chromatograph is equipped with a 200-nm detector and a 4.6-mm × 25-cm column that contains packing L1. The flow rate is about 1.0 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the resolution, R, between the norethindrone and ethinyl estradiol peaks is not less than 2.0; the column efficiency determined from the internal standard peak is not less than 8000 theoretical plates; and the relative standard deviation for six replicate injections is not more than 2.0% (both peaks).
Procedure Separately inject equal volumes (about 25 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. The relative retention times are about 0.9 for ethinyl estradiol and 1.0 for norethindrone. Calculate the quantities, in mg, of norethindrone (C20H26O2) and ethinyl estradiol (C20H24O2) in each Tablet taken by the formula:
20C(RU / RS)in which C is the concentration, in mg per mL, of the appropriate USP Reference Standard in the Mixed standard preparation, and RU and RS are the peak response ratios, at corresponding retention times, obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information Please check for your question in the FAQs before contacting USP.
USP35NF30 Page 4076Pharmacopeial Forum: Volume No. 33(6) Page 1194