Medium: water; 900 mL.

Apparatus 2: 25 rpm.

Time: 30 minutes.

Procedure— Accurately weigh 5.0 mL of the constituted Oral Suspension, and transfer to the dissolution vessel. Determine the amount of cefadroxil dissolved by employing UV absorption at the wavelength of maximum absorbance at about 263 nm on filtered portions of the solution under test, suitably diluted with Medium, if necessary, in comparison with a Standard solution having a known concentration of USP Cefadroxil RS in the same Medium. Calculate the amount of cefadroxil dissolved by the formula: in which AU and AS are the absorbances obtained from the solution under test and the Standard solution, respectively; CS is the concentration, in mg per mL, of the Standard solution; 900 is the volume, in mL, of Medium; 100 is the conversion factor to percentage; W is the weight, in mg, of the 5 mL of constituted Oral Suspension taken; D is the dilution factor of the solution under test; and LC is the label claim, in mg per 5 mL.

Tolerances— Not less than 75% (Q) of the labeled amount of cefadroxil is dissolved in 30 minutes.

For solid packaged in single-unit containers: meets the requirements.

pH 5.0 Buffer, Mobile phase, Standard preparation, and Chromatographic system— Proceed as directed in the Assay under Cefadroxil.

Assay preparation— Constitute a container of Cefadroxil for Oral Suspension as directed in the labeling. Transfer an accurately measured volume of the oral suspension thus obtained, equivalent to about 250 mg of cefadroxil, to a 250-mL volumetric flask, dilute with pH 5.0 buffer to volume, and stir by mechanical means for 5 minutes. Pass about 25 mL of the resulting solution through a suitable filter of 0.8 µm or finer porosity, and use the clear filtrate as the Assay preparation. Use this solution on the day prepared.

Procedure— Proceed as directed for Procedure in the Assay under Cefadroxil. Calculate the quantity, in mg, of C16H17N3O5S in each mL of Cefadroxil for Oral Suspension taken by the formula: in which V is the volume, in mL, of Cefadroxil for Oral Suspension taken, and the other terms are as defined therein.