» Spironolactone Tablets contain not less than 95.0 percent and not more than 105.0 percent of the labeled amount of spironolactone (C24H32O4S).
Packaging and storage Preserve in tight, light-resistant containers.
Identification Mix a quantity of finely powdered Tablets, equivalent to about 100 mg of spironolactone, with 25 mL of methanol, and filter. Apply 10 µL of this solution and 10 µL of a solution of USP Spironolactone RS in methanol containing 4 mg per mL to a suitable thin-layer chromatographic plate (see Chromatography 621) coated with a 0.25-mm layer of chromatographic silica gel mixture. Develop the chromatogram in a solvent system consisting of a mixture of chloroform, ethyl acetate, and methanol (2:2:1) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and allow the solvent to evaporate. Locate the spots on the plate by viewing under short-wavelength UV light: the RF value of the principal spot obtained from the solution under test corresponds to that obtained from the Standard solution.
Medium: 0.1 N hydrochloric acid containing 0.1% of sodium lauryl sulfate; 1000 mL.
Apparatus 2: 75 rpm.
Time: 60 minutes.
Procedure Determine the amount of C24H32O4S dissolved using UV absorption at the wavelength of maximum absorbance at about 242 nm obtained on filtered portions of the solution under test, diluted with Medium, if necessary, in comparison with a Standard solution having a known concentration of USP Spironolactone RS in the same Medium. [noteA volume of alcohol not exceeding 1% of the final volume of the solution may be used to prepare the Standard solution.]
Tolerances Not less than 75% (Q) of the labeled amount of C24H32O4S is dissolved in 60 minutes.
Uniformity of dosage units 905: meet the requirements.
Mobile phase, Standard preparation, and Chromatographic system Prepare as directed in the Assay under Spironolactone.
Diluent Prepare a mixture of acetonitrile and water (1:1).
Assay preparation Accurately weigh not fewer than 10 Tablets, and transfer to a suitable volumetric flask. [noteThe target concentration is about 1 mg per mL.] Add a sufficient quantity of Diluent, shake for about 30 minutes, and sonicate for 30 minutes or until the Tablets are disintegrated. Cool the solution to room temperature, dilute with Diluent to volume, and centrifuge a suitable portion of the mixture. Quantitatively dilute a portion of this solution with Diluent to obtain a solution having a known concentration of about 0.5 mg of spironolactone per mL.
Procedure Proceed as directed for Procedure in the Assay under Spironolactone. Calculate the quantity, in mg, of spironolactone (C24H32O4S) in the portion of Tablets taken by the formula:
CD(rU / rS)in which C is the concentration, in mg per mL, of USP Spironolactone RS in the Standard preparation; D is the dilution factor for the Assay preparation; and rU and rS are the peak responses for spironolactone obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information Please check for your question in the FAQs before contacting USP.Chromatographic Column
USP32NF27 Page 3593Pharmacopeial Forum: Volume No. 31(1) Page 74
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.