Conjugated Estrogens Tablets
» Conjugated Estrogens Tablets contain not less than 73.0 percent and not more than 95.0 percent of the labeled amount of conjugated estrogens as the total of sodium estrone sulfate and sodium equilin sulfate. The ratio of sodium equilin sulfate to sodium estrone sulfate in the Tablets is not less than 0.35 and not more than 0.65.
Packaging and storage
Preserve in well-closed containers.
Labeling
The labeling indicates the Tablet strength and states with which in vitro Dissolution Test the product complies.
Identification
Tablets respond to the Identification tests under Conjugated Estrogens.
Dissolution 711
Proceed as directed for Extended-Release Articles.
test 1
(for products labeled as 0.3-, 0.45-, and 0.625-mg tablets)If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 1.
Medium:
water; 900 mL.
Apparatus 2:
50 rpm.
Times:
2, 5, and 8 hours.
Mobile phase
Prepare a filtered and degassed mixture of 0.025 M monobasic potassium phosphate and acetonitrile (3:1). Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard solution
Transfer 10 Tablets to a 1000-mL volumetric flask, dilute with water to volume, and stir vigorously by mechanical means for at least 3 hours. Pipet a filtered 100-mL aliquot of the solution into a 900-mL volumetric flask, and dilute with water to volume.
Test solution
Filter a portion of the solution under test. [noteIt is recommended that the filters selected be tested for binding affinity. ]
Chromatographic system
The liquid chromatograph is equipped with a 205-nm detector and a 4.6-mm × 3.0-cm column that contains 3-µm packing L1. The flow rate is about 1.5 mL per minute. Chromatograph replicate injections of the Standard solution, and record the responses as directed for Procedure: the relative retention times are about 0.9 for equilin sulfate and 1.0 for estrone sulfate, the estrone sulfate peak being the last major peak in the chromatogram; the resolution, R, between equilin sulfate and estrone sulfate is not less than 1.5; and the relative standard deviation for the estrone sulfate peak is not more than 1.5%. [noteIf estrone is present it may be retained on the column for a period longer than 50 minutes and interfere in later chromatographic runs. ]
Procedure
Separately inject equal volumes (between 20 and 200 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the responses for the estrone sulfate peaks. Calculate the percentage of estrone sodium sulfate released by the formula:
100(rU / rS)
in which rU and rS are the peak responses obtained from the Test solution and the Standard solution, respectively.
Times and Tolerances
The percentages of estrone sodium sulfate dissolved at the times specified conform to Acceptance Table 2.
test 2
(for products labeled as 0.9-mg tablets)If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 2.
Medium, Apparatus, Times, Mobile phase, Standard solution, Test solution, Chromatographic system, and Procedure
Proceed as directed for Test 1.
Times and Tolerances
The percentages of estrone sodium sulfate dissolved at the times specified conform to Acceptance Table 2.
test 3
(for products labeled as 1.25- and 2.50-mg tablets)If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 3.
Medium, Apparatus, Mobile phase, Standard solution, Test solution, Chromatographic system, and Procedure
Proceed as directed for Test 1.
Times:
2, 5, 8, and 12 hours.
Times and Tolerances
The percentages of estrone sodium sulfate dissolved at the times specified conform to Acceptance Table 2.
test 4
(for products labeled as 1.25-mg tablets)If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 4.
Medium:
acetate buffer, pH 4.5; 900 mL.
Apparatus 2:
50 rpm, with sinkers.
Times:
2, 4, 8, and 12 hours.
Mobile phase
Prepare a filtered and degassed mixture of 0.025 M monobasic potassium phosphate and acetonitrile (78:22). Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard solution
Accurately weigh 20 Tablets and determine the average tablet weight. Grind the Tablets to a uniform fine powder. Accurately weigh a portion of the powdered Tablets equivalent to the average tablet weight, transfer to a 900-mL volumetric flask, and dilute with Medium to volume. Stir vigorously by mechanical means for at least 2 hours or until the dissolution of the powder is complete. Pass a portion of the extract through a suitable 10-µm filter.
Test solution
Pass a portion of the solution under test through a suitable 10-µm filter. [noteIt is recommended that the filters selected be tested for binding affinity. ]
Chromatographic system (see Chromatography 621)
The liquid chromatograph is equipped with a 210-nm detector and a 3.2-mm × 5.0-cm column that contains 5-µm packing L1. The flow rate is about 0.8 mL per minute. Chromatograph replicate injections of the Standard solution, and record the responses as directed for Procedure: the relative retention times are about 0.9 for equilin sulfate and 1.0 for estrone sulfate, the estrone sulfate peak being the last major peak in the chromatogram; the resolution, R, between equilin sulfate and estrone sulfate is not less than 1.2; and the relative standard deviation for the estrone sulfate peak is not more than 2.0%. [noteIf estrone is present, it may be retained on the column for a period longer than 50 minutes and interfere in later chromatographic runs. ]
Procedure
Separately inject equal volumes (between 20 and 200 µL) of the Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the responses for the estrone sulfate peaks. Calculate the percentage of estrone sulfate released by the formula:
in which rU and rS are the peak responses obtained from the Test solution and the Standard solution, respectively.
Times and Tolerances
The percentages of estrone sodium sulfate dissolved at the times specified conform to Acceptance Table 2.
test 5
(for products labeled as 0.3-, 0.45-, and 0.625-mg tablets)If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 5.
Medium, Apparatus, Mobile phase, Standard solution, Test solution, Chromatographic system, and Procedure
Proceed as directed for Test 4.
Times:
1, 3, and 8 hours.
Times and Tolerances
The percentages of estrone sodium sulfate dissolved at the times specified conform to Acceptance Table 2.
test 6
(for products labeled as 0.9-mg tablets)If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 6.
Medium, Apparatus, Mobile phase, Standard solution, Test solution, Chromatographic system, and Procedure
Proceed as directed for Test 4.
Times:
1, 3, and 8 hours.
Times and Tolerances
The percentages of estrone sodium sulfate dissolved at the times specified conform to Acceptance Table 2.
Uniformity of dosage units
Assay 10 individual Tablets as directed in the Assay, and calculate the average content of conjugated estrogens, as the average of the total contents of sodium estrone sulfate and sodium equilin sulfate, in the 10 Tablets. The requirements are met if the content of each of the Tablets is not less than 85.0% and not more than 115.0% of the average content of conjugated estrogens. If the content of not more than 2 Tablets falls outside the range of 85.0% to 115.0% of the average content but not outside the range of 75.0% to 125.0%, assay an additional 20 Tablets. The requirements are met if the content of not more than 2 of the 30 Tablets falls outside the limits of 85.0% and 115.0% of that average, and no unit is outside the range of 75.0% to 125.0% of the average content.
Assay
Internal standard solution, Stock solution, pH 5.2 Acetate buffer, System suitability solution, Standard preparation, and Chromatographic system
Proceed as directed in the Assay under Conjugated Estrogens.
Assay preparation
If the Tablets are sugar-coated, carefully remove the color and sugar coatings with water, leaving the shellac coating intact, and dry under nitrogen. Weigh and finely powder not fewer than 20 of the Tablets. Transfer an accurately weighed quantity of the powder, equivalent to about 2 mg of total conjugated estrogens, to a 50-mL centrifuge tube fitted with a polytef-lined screw-cap and containing 15 mL of pH 5.2 Acetate buffer and 1 g of barium chloride. Proceed as directed in the Assay preparation under Conjugated Estrogens, beginning with Cap the tube tightly.
Procedure
Separately inject equal volumes (about 1 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Separately calculate the quantities, in mg, of sodium estrone sulfate and sodium equilin sulfate in the portion of Tablets taken by the formula:
0.005(1.381CS)(RU / RS)
in which 1.381 is the factor converting free estrogen to the conjugate sodium salt; CS is the concentration, in µg per mL, of USP Estrone RS or USP Equilin RS in the Stock solution; and RU and RS are the ratios of the peak response of the appropriate analyte to that of the internal standard 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 3114
Pharmacopeial Forum: Volume No. 32(4) Page 1074
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