Packaging and storage— Preserve in tight containers.

USP Reference standards á11ñ— USP Nystatin RS.USP Triamcinolone Acetonide RS.

Identification— Place 2g of Ointment in a conical flask,add 5.0mLof chloroform,and shake for 10minutes.Add 15mLof alcohol,and shake for an additional 10minutes.Filter the solution into a centrifuge tube,and evaporate the filtrate to dryness.Dissolve the residue in alcohol to obtain a solution containing about 250µg of triamcinolone acetonide per mL.Proceed as directed in the Identificationtest under Triamcinolone Acetonide Cream,beginning with “Apply 10µLof this solution”:the specified result is observed.

Minimum fill á755ñ: meets the requirements.

Water,Method Iá921ñ: not more than 0.5%,20mLof a mixture of toluene and methanol (7:3)being used in place of methanol in the titration vessel.

Assay for nystatin— Proceed as directed for nystatin under Antibiotics—Microbial Assays á81ñ,blending a suitable,accurately weighed portion of Ointment in a high-speed blender for 3to 5minutes with a sufficient,accurately measured volume of dimethylformamide to give a convenient concentration.Dilute an accurately measured volume of the solution so obtained quantitatively with dimethylformamide to obtain a stock solution containing about 400USP Nystatin Units per mL.Dilute an accurately measured volume of this stock solution quantitatively with Buffer No.6to obtain a Test Dilutionhaving a concentration of nystatin assumed to be equal to the median dose level of the Standard.

Assay for triamcinolone acetonide— Proceed with Ointment as directed in the Assayunder Triamcinolone Acetonide Cream,except to read “Ointment”in place of “Cream”throughout.

Expert Committee:(PA7)Pharmaceutical Analysis 7

USP28–NF23Page 1411

Phone Number:1-301-816-8335