Dexamethasone Topical Aerosol
»Dexamethasone Topical Aerosol is Dexamethasone in a suitable lotion base mixed with suitable propellants in a pressurized container.Dexamethasone Topical Aerosol delivers not less than 90.0percent and not more than 120.0percent of the labeled amount of C22H29FO5.
Packaging and storage— Preserve in pressurized containers,and avoid exposure to excessive heat.
Identification— Evaporate 5mLof the Assay preparation,obtained as directed in the Assay,on a steam bath just to dryness,and dissolve the residue in 1mLof chloroform.Apply 100µLof this solution and 10µLof a solution of USP Dexamethasone RSin chloroform containing 500µg per mLto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)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 (1in 2)and heating on a hot plate or under a heat lamp until spots appear:the RFvalue of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution.
Microbial limits á61ñ— It meets the requirements of the tests for absence of Staphylococcus aureusand Pseudomonas aeruginosa.
Other requirements— It meets the requirements for Pressure Test,Minimum Fill,and Leakage Testunder Aerosols,Nasal Sprays,Metered-Dose Inhalers,and Dry Powder Inhalers á601ñ.
Assay—
Standard preparation— Prepare as directed under Assay for Steroids á351ñ,using USP Dexamethasone RS.
Assay preparation— Shake the Topical Aerosol container gently,and invert,immersing the valve in about 75mLof alcohol contained in a 400-mLbeaker.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-mLvolumetric flask,dilute with alcohol to volume,and mix.Dilute an accurately measured volume of this solution,equivalent to about 1mg of dexamethasone,with alcohol to 100.0mL,and mix.Transfer 20.0mLof this solution to a glass-stoppered,50-mLflask.
Procedure— Proceed as directed for Procedureunder Assay for Steroids á351ñ,except to allow to stand in the dark for 45minutes.Calculate the quantity,in mg,of C22H29FO5in each container taken by the formula:
(10C/V)(AU/AS),
in which Vis the volume,in mL,of assay solution taken for the second dilution.
Auxiliary Information— Staff Liaison:Clydewyn M.Anthony,Ph.D.,Scientist
Expert Committee:(PA1)Pharmaceutical Analysis 1
USP28–NF23Page 588
Phone Number:1-301-816-8139