Medium: 0.05 M potassium phosphate buffer, pH 7.2, prepared by dissolving 6.8 g of monobasic potassium phosphate in 1000 mL of water and adjusting with 1 N sodium hydroxide to a pH of 7.2; 900 mL.

Apparatus 1: 100 rpm.

Time: 45 minutes.

Procedure— Determine the amount of cefixime (C16H15N5O7S2) dissolved from UV absorbances at the wavelength of maximum absorbance at about 288 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 Cefixime RS in the same medium. [NOTE—An amount of methanol not to exceed 0.1% of the total volume of the Standard solution may be used to bring the Reference Standard into solution prior to dilution with Dissolution Medium, and the solution may be sonicated to assure complete dissolution of the Reference Standard.]

Tolerances— Not less than 75% (Q) of the labeled amount of cefixime (C16H15N5O7S2) is dissolved in 45 minutes.

(Official January 1, 2007)

Tetrabutylammonium hydroxide solution, Mobile phase, pH 7.0 Phosphate buffer, Resolution solution, Standard preparation, and Chromatographic system— Proceed as directed in the Assay under Cefixime.

Assay preparation— Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed portion of the powder, equivalent to about 400 mg of cefixime, to a 100-mL volumetric flask, add 75 mL of pH 7.0 Phosphate buffer, and sonicate. Dilute with pH 7.0 Phosphate buffer to volume, mix, and centrifuge. Transfer 5.0 mL of the clear supernatant to a second 100-mL volumetric flask, dilute with pH 7.0 Phosphate buffer to volume, and mix.

Procedure— Proceed as directed in the Assay under Cefixime. Calculate the quantity, in mg, of cefixime (C16H15N5O7S2) in the portion of Tablets taken by the formula: in which the terms are as defined therein.