Medium: 0.05MpH6.8potassium phosphate buffer;900mL.

Apparatus 1: 100rpm.

Time: 30minutes.

Procedure— Determine the amount of cloxacillin (C19H18ClN3O5S)dissolved by employing the method set forth in the Assay,in comparison with a Standard solution having a known concentration of USP Cloxacillin Sodium RSin the Dissolution Medium.

Tolerances— Not less than 80%(Q)of the labeled amount of cloxacillin (C19H18ClN3O5S)is dissolved in 30minutes.

Buffer,Mobile phase,Standard preparation,and Chromatographic system— Proceed as directed in the Assayunder Cloxacillin Sodium.

Assay preparation— Weigh and finely powder the contents of not fewer than 10Capsules.Transfer an accurately weighed quantity of the powder,equivalent to about 100mg of cloxacillin,to a 200-mLvolumetric flask,dilute with Bufferto volume,mix,and stir for 10minutes.Filter about 25mLof this mixture,discarding the first 5mLof the filtrate.Use the clear filtrate as the Assay preparation.

Procedure— Proceed as directed for Procedurein the Assayunder Cloxacillin Sodium.Calculate the quantity,in mg,of cloxacillin (C19H18ClN3O5S)in the portion of Capsule contents taken by the formula: in which the terms are as defined therein.