Nystatin,Neomycin Sulfate,Thiostrepton,and Triamcinolone Acetonide Ointment
»Nystatin,Neomycin Sulfate,Thiostrepton,and Triamcinolone Acetonide Ointment contains not less than 90.0percent and not more than 130.0percent of the labeled amounts of nystatin,neomycin,and thiostrepton,and not less than 90.0percent and not more than 110.0percent of the labeled amount of triamcinolone acetonide (C24H31FO6).
Packaging and storage— Preserve in tight containers.
Labeling— Label it to indicate that it is for veterinary use only.
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.
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 neomycin— Proceed as directed for the turbidimetric assay for neomycin under Antibiotics—Microbial Assays á81ñ,placing an accurately weighed portion of Ointment,equivalent to about 2.5mg of neomycin,in a 250-mLconical flask,and treating it as follows.Add 50mLof hexanes,and shake to disperse the Ointment.Transfer the mixture to a 250-mLseparator.Wash the flask with 50mLof 0.01Nhydrochloric acid,with shaking,and transfer the washing to a separator.Stopper the separator,shake,and allow the layers to separate.Draw off the lower aqueous layer,collecting it in a 250-mLvolumetric flask.Repeat the extraction of the hexanes layer remaining in the separator with two or more 50-mLportions of 0.01Nhydrochloric acid,combining the aqueous extracts in the 250-mLvolumetric flask.Dilute the contents of the volumetric flask with 0.01Nhydrochloric acid to volume,and mix.Dilute this solution quantitatively and stepwise with Buffer No.3to obtain a Test Dilutionhaving a concentration assumed to be equal to the median dose of the Standard.
Assay for thiostrepton— Proceed as directed for thiostrepton under Antibiotics—Microbial Assays á81ñ,blending a suitable,accurately weighed portion of Ointment in a high-speed blender with a sufficient,accurately measured volume of dimethyl sulfoxide to give a convenient concentration,and filter.Dilute an accurately measured volume of the filtrate so obtained quantitatively with dimethyl sulfoxide to obtain a Test Dilutionhaving a concentration of thiostrepton assumed to be equal to the median dose of the Standard.
Assay for triamcinolone acetonide— Proceed with Ointment as directed in the Assayunder Triamcinolone Acetonide Cream,but read “Ointment”in place of “Cream”throughout.
Auxiliary Information— Staff Liaison:Ian DeVeau,Ph.D.,Senior Scientist
Expert Committee:(VET)Veterinary Drugs
USP28–NF23Page 1410
Phone Number:1-301-816-8178