Assay
Mobile phase, Standard preparation, and Chromatographic system
Proceed as directed in the
Assay under
Griseofulvin.
Sodium chloride solution
Dissolve a suitable quantity of sodium chloride in water to obtain a solution containing about 0.1 g per mL.
Assay preparation
Transfer an accurately measured volume of Oral Suspension, freshly mixed and free from air bubbles, equivalent to about 125 mg of griseofulvin, to a glass-stoppered, 50-mL centrifuge tube. Add 20 mL of Sodium chloride solution and 20 mL of methylene chloride. Insert the stopper into the tube, and mix by rotating the tube for 10 minutes. Separate the phases by centrifugation, carefully remove the lower methylene chloride layer with a needle and syringe, and filter through methylene chloride-prerinsed anhydrous sodium sulfate into a 100-mL volumetric flask. Repeat the extraction with two additional 20-mL portions of methylene chloride, combining the extracts in the volumetric flask. Dilute with methylene chloride to volume, and mix. Transfer 5.0 mL of the resulting solution to a 50-mL volumetric flask, and evaporate on a steam bath under a stream of nitrogen to dryness. Transfer 4.0 mL of Mobile phase to the flask, swirl to dissolve the residue, 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 (C
17H
17ClO
6) in each mL of the Oral Suspension taken by the formula:
(PC / V)(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Griseofulvin RS in the
Standard preparation; V is the volume, in mL, of Oral Suspension taken; and the other terms are as defined therein.