Medium: water; use 500 mL of the Dissolution Medium for Tablets labeled to contain 10 mg of prednisone or less, and 900 mL for Tablets labeled to contain more than 10 mg of prednisone.

Apparatus 2: 50 rpm.

Time: 30 minutes.

Procedure— Determine the amount of C21H26O5 dissolved from UV absorbances at the wavelength of maximum absorbance at about 242 nm of filtered portions of the solution under test, suitably diluted with Dissolution Medium, if necessary, in comparison with a Standard solution having a known concentration of USP Prednisone RS in the same medium. An amount of alcohol not to exceed 5% of the total volume of the Standard solution may be used to bring the prednisone standard into solution prior to dilution with water.

Tolerances— Not less than 80% (Q) of the labeled amount of C21H26O5 is dissolved in 30 minutes.

Procedure for content uniformity—

Mobile phase, Internal standard solution, Standard preparation, and Chromatographic system— Proceed as directed in the Assay under Prednisone.

Test preparation— Place 1 Tablet in a volumetric flask of such size that when the contents are diluted to volume the resulting solution has a concentration of about 0.2 mg of prednisone per mL. Add 5 mL of water, swirl, sonicate for 1 minute, add a volume of methanol equal to one-half the volume of the volumetric flask, and sonicate again for 1 minute. Dilute with water to volume, and mix. Transfer 5.0 mL of this solution and 5.0 mL of the Internal standard solution to a 50-mL volumetric flask, add dilute methanol (1 in 2) to volume, and mix. Filter through a 5-µm filter, discarding the first 20 mL of the filtrate.

Procedure— Proceed as directed for Procedure in the Assay under Prednisone, except to calculate the quantity, in mg, of C21H26O5 in the Tablet taken by the formula: in which D is the dilution factor for the Test preparation and the other terms are as defined therein.

Mobile phase, Internal standard solution, Standard preparation, and Chromatographic system— Proceed as directed in the Assay under Prednisone.

Assay preparation— Weigh and finely powder not less than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 20 mg of prednisone, to a 100-mL volumetric flask. Add 5 mL of water, sonicate for 1 minute, add 50 mL of methanol, and sonicate again for 1 minute. Dilute with water to volume, and mix. Transfer 5.0 mL of this solution and 5.0 mL of the Internal standard solution to a 50-mL volumetric flask, add dilute methanol (1 in 2) to volume, and mix. Filter through a 5-µm filter, discarding the first 20 mL of the filtrate.

Procedure— Proceed as directed for Procedure in the Assay under Prednisone, except to calculate the quantity, in mg, of C21H26O5 in the portion of Tablets taken by the formula: in which the terms are as defined therein.