Triamcinolone Acetonide Topical Aerosol »Triamcinolone Acetonide Topical Aerosol is a solution of Triamcinolone Acetonide in a suitable propellant in a pressurized container.It contains not less than 90.0percent and not more than 115.0percent of the labeled amount of C24H31FO6. Packaging and storage— Preserve in pressurized containers,and avoid exposure to excessive heat. USP Reference standards á11ñ USP Triamcinolone Acetonide RS. Identification— Apply 20µLof a solution prepared as directed for Assay preparationin the Assaybut without the addition of the Internal standard solution,and 20µLof a solution of USP Triamcinolone Acetonide RSin methanol containing 30µg per mL,to a line parallel to and about 1.5cm from the bottom edge of a thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel.Proceed as directed in the Identificationtest under Triamcinolone Acetonide Cream,beginning with “Place the plate in a developing chamber.”The specified result is obtained. 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— Mobile phase— Prepare a degassed solution of water and acetonitrile (70:30). Internal standard solution— Dissolve fluoxymesterone in methanol to obtain a solution having a concentration of about 25µg per mL. Standard preparation— Dissolve an accurately weighed quantity of USP Triamcinolone Acetonide RSin methanol to obtain a solution having a concentration of about 100µg per mL.Transfer 15.0mLof this solution to a 50-mLvolumetric flask,add 25.0mLof Internal standard solution,dilute with methanol to volume,and mix.This solution has a known concentration of about 30µg per mL. Assay preparation— Fit the valve of a previously weighed Triamcinolone Acetonide Aerosol container with a suitable tube assembly so that the contents can be sprayed directly into the bulb portion of a 100-mLvolumetric flask containing 50.0mLof Internal standard solutionand 20mLof methanol.Spray a portion of the contents,equivalent to about 3mg of triamcinolone acetonide,into the flask,determining the exact amount sprayed by difference.Place in a sonic bath for about 5minutes to expel the propellant.Dilute with methanol to volume,and mix.[NOTE—The propellant is extremely flammable.When evaporating,observe proper precautions and work under an explosion-proof hood.] Procedure— Introduce equal volumes (between 15µLand 25µL)of the Assay preparationand the Standard preparationinto a chromatograph (see Chromatography á621ñ)operated at room temperature and fitted with a 3.9-mm ×30-cm column,packed with packing L1,and equipped with a 254-nm detector.Adjust the operating parameters and the Mobile phasecomposition such that the separation of triamcinolone acetonide and internal standard is optimized,with a retention time of about 14minutes for triamcinolone acetonide.In a suitable system,the relative standard deviation for five replicate injections of the Standard preparationis not more than 3.0%.Measure the responses of the internal standard and triamcinolone acetonide peaks at the same retention times obtained from the Assay preparationand the Standard preparation.Calculate the quantity,in µg,of C24H31FO6in the portion of Topical Aerosol taken by the formula: 100C(RU/RS), in which Cis the concentration,in µg per mL,of USP Triamcinolone Acetonide RSin the Standard preparation,and RUand RSare the ratios of the peak responses of triamcinolone acetonide to internal standard obtained from the Assay preparationand the Standard preparation,respectively. Auxiliary Information— Staff Liaison:Clydewyn M.Anthony,Ph.D.,Scientist Expert Committee:(PA1)Pharmaceutical Analysis 1 USP28–NF23Page 1959 Phone Number:1-301-816-8139