Norethindrone Acetate and Ethinyl Estradiol Tablets
»Norethindrone Acetate and Ethinyl Estradiol Tablets contain not less than 90.0percent and not more than 110.0percent of the labeled amount of norethindrone acetate (C22H28O3),and not less than 88.0percent and not more than 112.0percent of the labeled amount of ethinyl estradiol (C20H24O2).
Packaging and storage—
Preserve in well-closed containers.
Identification—
A:Infrared Absorption á197Kñ—
Test specimen—
Wash the isooctane-toluene solution obtained in the Assay for ethinyl estradiolwith 5mLof water,filter,and evaporate to dryness.
B:Thin-Layer Chromatographic Identification Test á201ñ—
Adsorbent—
Use either a 0.1-mm or a 0.25-mm layer of chromatographic silica gel mixture as described in the chapter.Activate the plate at 105
for 60minutes immediately prior to use.
for 60minutes immediately prior to use.
Test solution—
Crush 1Tablet in 1mLof alcohol in a 15-mLconical centrifuge tube,and centrifuge briefly.
Standard solution 1:
an alcohol solution containing in each mLan amount of USP Norethindrone Acetate RS,accurately weighed,corresponding to the labeled quantity of norethindrone acetate per Tablet.
Standard solution 2:
an alcohol solution containing in each mL50µg of USP Ethinyl Estradiol RS,accurately weighed.
Application volume:
5µL.
Developing solvent system:
a mixture of chloroform and glacial acetic acid (95:5).
Procedure—
Proceed as directed in the chapter,except to heat the plate in an oven at 105for 10minutes after the solvent evaporates.Remove the plate from the oven,and while it is still hot,spray lightly with dilute sulfuric acid (3in 4).Observe the plate under long-wavelength UVlight:any red fluorescent spot produced by the Test solutionat an RFvalue of about 0.4,and any yellow fluorescent spot produced by the Test solutionat an RFvalue of about 0.2,are not greater in size and intensity than the corresponding spots from Standard solution 1and Standard solution 2,respectively.
for 10minutes after the solvent evaporates.Remove the plate from the oven,and while it is still hot,spray lightly with dilute sulfuric acid (3in 4).Observe the plate under long-wavelength UVlight:any red fluorescent spot produced by the Test solutionat an RFvalue of about 0.4,and any yellow fluorescent spot produced by the Test solutionat an RFvalue of about 0.2,are not greater in size and intensity than the corresponding spots from Standard solution 1and Standard solution 2,respectively.
Dissolution á711ñ—
0.025M Acetate buffer solution—
Accurately weigh about 5.22g of anhydrous sodium acetate and 2.2g of glacial acetic acid into a 4-liter volumetric flask,add 3.5liters of water,and mix.Adjust with 1Nsodium hydroxide to a pHof 5.0±0.2,and dilute with water to volume.
Medium:
0.025MpH5.0acetate buffer with 0.15%sodium lauryl sulfate,prepared by accurately weighing about 6g of sodium lauryl sulfate into a 4-liter volumetric flask,adding 1.5liters of 0.025M Acetate buffer solution,mixing,and diluting with 0.025M Acetate buffer solutionto volume;600mL.
Apparatus 2:
75rpm.
Time:
60minutes.
Determine the amounts of norethindrone acetate (C22H28O3)and ethinyl estradiol (C20H24O2)dissolved by employing the following method.
Mobile phase—
Prepare a filtered and degassed mixture of 0.2%phosphoric acid,acetonitrile,and tetrahydrofuran (540:380:80).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).
Standard solution—
Dissolve accurately weighed quantities of USP Norethindrone Acetate RSand USP Ethinyl Estradiol RSin a minimum amount of acetonitrile,and dilute quantitatively,and stepwise if necessary,with Dissolution Mediumto obtain a solution having known concentrations equivalent to the expected concentrations of the solution under test.
Test solution—
Withdraw a 2-mLaliquot using a glass pipet or syringe,and centrifuge at about 2000rpm for about 5minutes.Use the supernatant as the Test solution.
Chromatographic system—
The liquid chromatograph is equipped with a 242-nm detector and a fluorescent detector with an excitation wavelength set at 210-nm,a 6-mm ×40-mm column that contains 3-µm packing L1and a 4-mm ×12.5-mm guard column that contains 5-µm packing L1.The flow rate is about 1mLper minute.
Procedure—
Separately inject equal volumes (about 200µL)of the Standard solutionand the Test solutioninto the chromatograph,record the chromatograms,and measure the peak heights.
Tolerances—
Not less than 80%(Q)of the labeled amounts of C22H28O3and C20H24O2is dissolved in 60minutes.
Uniformity of dosage units á905ñ:
meet the requirements.
Procedure for content uniformity for ethinyl estradiol—
Place 1Tablet in a 125-mLseparator,add 5mLof water,and shake until the Tablet has disintegrated completely.Add 25.0mLof a mixture of toluene and isooctane (3:2),shake thoroughly,allow to settle,and remove and discard the aqueous phase.Transfer 20.0mLof the isooctane-toluene solution to a second 125-mLseparator,avoiding mechanical transfer of any of the aqueous phase.Transfer 8.0mLof a solution of USP Ethinyl Estradiol RSin toluene,containing in each mLan amount of ethinyl estradiol equal to one-tenth of the labeled quantity per Tablet,to a third 125-mLseparator,and add 12mLof isooctane.To the second and third separators add 8.0mLof a 1in 25solution of sodium hydroxide in dilute alcohol (1in 10),shake,allow to settle,and transfer the sodium hydroxide solution from each separator into separate suitable containers.Proceed as directed in the Assay for ethinyl estradiol,beginning with “Add,dropwise,5.0mLof the sodium hydroxide extract”,but determine the absorbances of the final solutions using 5-cm cells.Calculate the quantity,in µg,of C20H24O2in the Tablet taken by the formula:
10C(AU/AS),
in which Cis the concentration,in µg per mL,of the Standard solution in toluene;and AUand ASare the absorbances of the test solution and the Standard solution,respectively.
Procedure for content uniformity for norethindrone acetate—
Transfer 1finely powdered Tablet to a 100-mLvolumetric flask with the aid of about 75mLof alcohol,heat to boiling,and allow to remain at a temperature just below the boiling temperature for about 15minutes,with occasional swirling.Cool to room temperature,dilute with alcohol to volume,and mix.Centrifuge a portion of the contents at about 2000rpm until the solution becomes clear.If necessary,dilute a portion of the supernatant quantitatively with alcohol to provide a solution containing about 10µg per mLof norethindrone acetate.Concomitantly determine the absorbances of this solution and of a solution of USP Norethindrone Acetate RSin alcohol having a known concentration of about 10µg per mLin 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 Tablet taken by the formula:
(T/D)C(AU/AS),
in which Tis the labeled quantity,in mg,of norethindrone acetate in the Tablet;Dis the concentration,in µg per mL,of norethindrone acetate in the test solution,based on the labeled quantity per Tablet and the extent of dilution;Cis the concentration,in µg per mL,of USP Norethindrone Acetate RSin the Standard solution;and AUand ASare the absorbances of the solution from the Tablet and the Standard solution,respectively.
Assay for norethindrone acetate—
Place 20Tablets in a 125-mLseparator,add 20mLof water,and shake until the Tablets have disintegrated completely.Extract with three 30-mLportions of chloroform,filtering each extract through chloroform-moistened cotton into a round-bottom,250-mLflask.Evaporate the combined extracts under vacuum to dryness,with the aid of gentle heat (not more than 40).Cool,add 5mLof water and 100.0mLof a mixture of isooctane and toluene (3:2),insert the stopper,and shake for 2to 3minutes.Transfer an accurately measured volume of the supernatant isooctane-toluene solution,containing about 1.5mg of norethindrone acetate,to a round-bottom,250-mLflask,and similarly evaporate under vacuum to dryness,taking care to assure complete removal of residual toluene.[NOTE—Retain the remaining isooctane-toluene solution for the Assay for ethinyl estradiol.]Dissolve the residue in 100.0mLof alcohol,and mix.Concomitantly determine the absorbances of this solution and a solution of USP Norethindrone Acetate RSin the same medium,having a known concentration of about 15µg per mL,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 norethindrone acetate (C22H28O3)in the accurately measured volume of isooctane-toluene solution of the Tablets taken by the formula:
).Cool,add 5mLof water and 100.0mLof a mixture of isooctane and toluene (3:2),insert the stopper,and shake for 2to 3minutes.Transfer an accurately measured volume of the supernatant isooctane-toluene solution,containing about 1.5mg of norethindrone acetate,to a round-bottom,250-mLflask,and similarly evaporate under vacuum to dryness,taking care to assure complete removal of residual toluene.[NOTE—Retain the remaining isooctane-toluene solution for the Assay for ethinyl estradiol.]Dissolve the residue in 100.0mLof alcohol,and mix.Concomitantly determine the absorbances of this solution and a solution of USP Norethindrone Acetate RSin the same medium,having a known concentration of about 15µg per mL,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 norethindrone acetate (C22H28O3)in the accurately measured volume of isooctane-toluene solution of the Tablets taken by the formula:
0.1C(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 from the Tablets and the Standard solution,respectively.
Assay for ethinyl estradiol—
Transfer 25.0mLof the isooctane-toluene solution prepared from the Tablets as directed in the Assay for norethindrone acetateto a 125-mLseparator,avoiding mechanical transfer of any of the aqueous phase.Transfer 10.0mLof a toluene solution of USP Ethinyl Estradiol RS,containing in each mLa known amount of ethinyl estradiol equal to one-half of the labeled quantity per Tablet,to another 125-mLseparator containing 15.0mLof isooctane.Add 10.0mLof a 1in 25solution of sodium hydroxide in dilute alcohol (1in 10)to each separator,and shake gently for 3minutes.Allow to settle,and transfer the sodium hydroxide solution from each separator into separate suitable containers.[NOTE—Retain the isooctane-toluene solution for Identification test A.]Add,dropwise,5.0mLof the sodium hydroxide extract from the Tablets to 25.0mLof dilute sulfuric acid (4in 5)contained in a 150-mLbeaker and previously chilled in an ice bath.Stir the acid solution continuously during the addition with the aid of a magnetic stirrer,and keep it in the ice bath.[NOTE—Stir the acid solution rapidly and introduce the alkaline solution near the perimeter of the rapidly swirling acid solution,rather than near the vortex.Add the alkaline solution slowly,dropwise.]Treat 5.0mLof the sodium hydroxide solution from the Standard in the same manner,and allow the solutions to reach room temperature.Concomitantly determine the absorbances of both solutions in 1-cm cells at the wavelength of maximum absorbance at about 536nm,with a suitable spectrophotometer,using water as the blank.[NOTE—Use 2-cm cells for Tablets labeled to contain 30µg or less of ethinyl estradiol.]Calculate the quantity,in µg,of ethinyl estradiol (C20H24O2)in the portion of isooctane-toluene solution taken by the formula:
10C(AU/AS),
in which Cis the concentration,in µg per mL,of USP Ethinyl Estradiol RSin the Standard solution;and AUand ASare the absorbances of the solutions from the Tablets and the Reference Standard,respectively.
Auxiliary Information—
Staff Liaison:Clydewyn M.Anthony,Ph.D.,Scientist
Expert Committee:(PA1)Pharmaceutical Analysis 1
USP28–NF23Page 1397
Pharmacopeial Forum:Volume No.27(6)Page 3320
Phone Number:1-301-816-8139