Spironolactone and Hydrochlorothiazide Tablets
» Spironolactone and Hydrochlorothiazide Tablets contain not less than 90.0 percent and not more than 110.0 percent of the labeled amounts of spironolactone (C24H32O4S) and hydrochlorothiazide (C7H8ClN3O4S2).
Packaging and storage Preserve in tight, light-resistant containers.
USP Reference standards 11
Identification The retention times of the major peaks in the chromatogram of the Assay preparation correspond to those in the chromatogram of the Standard preparation, as obtained in the Assay.
Medium: 0.1 N hydrochloric acid containing 0.1% sodium lauryl sulfate; 900 mL.
Apparatus 2: 75 rpm.
Time: 60 minutes.
Determine the amounts of spironolactone and hydrochlorothiazide dissolved using the following method.
Standard solution Prepare a solution of USP Spironolactone RS and USP Hydrochlorothiazide RS in a mixture of methanol and Medium (1:1) having accurately known concentrations of about 0.0125 mg of each per mL.
Test solution Transfer a 5.0-mL portion of the solution under test to a 10-mL volumetric flask, dilute with methanol to volume, and mix.
Solution A Use acetonitrile.
Solution B Transfer about 4.5 g of monobasic potassium phosphate to a 1-L volumetric flask containing about 500 mL of water. Dissolve in and dilute with water to volume, and mix.
Mobile phase Use variable amounts of Solution A and Solution B as directed for Chromatographic system. Make adjustments if necessary (see System Suitability under Chromatography 621).
Chromatographic system (see Chromatography 621) 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 1 mL per minute. The chromatograph is programmed as follows.
Procedure Proceed as directed in the Assay, injecting 20 µL of each solution.
Tolerances Not less than 75% (Q) of each of the labeled amounts of C24H32O4S and C7H8ClN3O4S2 is dissolved in 60 minutes.
Uniformity of dosage units 905: meet the requirements for Content uniformity with respect to spironolactone and to hydrochlorothiazide.
Mobile phase Prepare a filtered and degassed mixture of methanol and water (7:3). Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard preparation Dissolve accurately weighed quantities of USP Spironolactone RS and USP Hydrochlorothiazide RS in methanol to obtain a solution having known concentrations of about 50 µg of each per mL.
Assay preparation Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 25 mg of spironolactone, to a 100-mL volumetric flask, add about 70 mL of methanol, shake by mechanical means for 30 minutes, dilute with methanol to volume, mix, and centrifuge. Transfer 20.0 mL of the resultant clear liquid to a 100-mL volumetric flask, dilute with methanol to volume, and mix.
Chromatographic system (see Chromatography 621) The liquid chromatograph is equipped with a 254-nm detector and a 4-mm × 30-cm column that contains packing L1. The flow rate is about 1 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the resolution, R, between hydrochlorothiazide and spironolactone is not less than 2.0; and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure Separately inject equal volumes (about 10 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 0.5 for hydrochlorothiazide and 1.0 for spironolactone. Calculate the quantity, in mg, of spironolactone (C24H32O4S) in the portion of Tablets taken by the formula:
0.5C(rU / rS)in which C is the concentration, in µg per mL, of USP Spironolactone RS in the Standard preparation; and rU and rS are the responses of the spironolactone peak obtained from the Assay preparation and the Standard preparation, respectively. Calculate the quantity, in mg, of hydrochlorothiazide (C7H8ClN3O4S2) by the same formula, changing the terms to refer to hydrochlorothiazide.
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