Medium: water containing 5.4 mg of sodium lauryl sulfate per mL; 1000 mL.

Apparatus 2: 50 rpm.

Time: 30 minutes.

Procedure— Determine the amount of C17H17ClO6 dissolved from UV absorbances at the wavelength of maximum absorbance at about 291 nm of filtered portions of the solution under test, suitably diluted with a solution of methanol and water (4:1), if necessary, in comparison with a Standard solution having a known concentration of USP Griseofulvin RS in the same medium.

Tolerances— Not less than 80% (Q) of the labeled amount of C17H17ClO6 is dissolved in 30 minutes.

Procedure for content uniformity— Transfer the contents of 1 Capsule to a suitable container, add an accurately measured volume of methanol sufficient to yield a concentration of griseofulvin not greater than 1 mg per mL, shake by mechanical means for 1 hour, or longer if necessary to disperse the specimen completely, and sonicate for 1 minute. Centrifuge a portion of this solution, and quantitatively dilute an accurately measured volume of the clear supernatant to obtain a test solution containing about 10 µg of griseofulvin per mL. Concomitantly determine the absorbances of the test solution and a Standard solution of USP Griseofulvin RS in methanol having a known concentration of about 10 µg per mL at the wavelength of maximum absorbance at about 292 nm, with a suitable spectrophotometer, using methanol as the blank. Calculate the quantity, in mg, of griseofulvin (C17H17ClO6) in the Capsule taken by the formula: in which C is the concentration, in µg per mL, of USP Griseofulvin RS in the Standard solution; L is the labeled quantity, in mg, of griseofulvin in the Capsule; D is the concentration, in µg per mL, of griseofulvin in the test solution, based on the labeled quantity per Capsule and the extent of dilution; and AU and AS are the absorbances of the test solution and the Standard solution, respectively.

(Official January 1, 2007)

Mobile phase, Standard preparation, and Chromatographic system— Proceed as directed in the Assay under Griseofulvin.

Assay preparation— Remove, as completely as possible, the contents of not fewer than 20 Capsules, and weigh accurately. Mix, and transfer an accurately weighed portion of the powder, equivalent to about 125 mg of griseofulvin, to a 100-mL volumetric flask. Add about 70 mL of methanol, shake by mechanical means for 30 minutes, dilute with methanol to volume, and mix. Filter a portion of this solution, discarding the first 5 mL of the filtrate. Transfer 5.0 mL of the clear filtrate to a 50-mL volumetric flask, dilute with Mobile phase to volume, and mix.

Procedure— Proceed as directed for Procedure in the Assay under Griseofulvin. Calculate the quantity, in mg, of griseofulvin (C17H17ClO6) in the portion of Capsules taken by the formula: in which C is the concentration, in mg per mL, of USP Griseofulvin RS in the Standard preparation, and the other terms are as defined therein.