Packaging and storage—
Preserve in pressurized containers, and avoid exposure to excessive heat.
Identification—
Evaporate 5 mL of the
Assay preparation, obtained as directed in the
Assay, on a steam bath just to dryness, and dissolve the residue in 1 mL of chloroform. Apply 100 µL of this solution and 10 µL of a solution of
USP Dexamethasone RS in chloroform containing 500 µg per mL to a suitable thin-layer chromatographic plate (see
Chromatography 
621
) coated with a 0.25-mm layer of chromatographic silica gel. Allow the spots to dry, and develop the chromatogram in a solvent system consisting of a mixture of chloroform and diethylamine (2:1) until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and allow the solvent to evaporate. Locate the spots on the plate by lightly spraying with dilute sulfuric acid (1 in 2) and heating on a hot plate or under a heat lamp until spots appear: the
RF value of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution.
Microbial limits 61—
It meets the requirements of the tests for absence of
Staphylococcus aureus and
Pseudomonas aeruginosa.
Assay—
Assay preparation—
Shake the Topical Aerosol container gently, and invert, immersing the valve in about 75 mL of alcohol contained in a 400-mL beaker. Actuate the valve by pushing against the bottom of the beaker. Remove the container at 15-second intervals, shake gently, and allow the container to warm to room temperature. Continue spraying until the contents of the container are exhausted. Transfer the alcohol solution to a 100-mL volumetric flask, dilute with alcohol to volume, and mix. Dilute an accurately measured volume of this solution, equivalent to about 1 mg of dexamethasone, with alcohol to 100.0 mL, and mix. Transfer 20.0 mL of this solution to a glass-stoppered, 50-mL flask.
Procedure—
Proceed as directed for
Procedure under
Assay for Steroids 351, except to allow to stand in the dark for 45 minutes. Calculate the quantity, in mg, of C
22H
29FO
5 in each container taken by the formula:
(10C / V)(AU / AS),
in which
V is the volume, in mL, of assay solution taken for the second dilution.
