Packaging and storage— Preserve in tight containers.

USP Reference standards 11— USP Gramicidin RS. USP Neomycin Sulfate RS.USP Nystatin RS. USP Triamcinolone Acetonide RS.

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

Minimum fill 755: meets the requirements.

Water, Method I 921: not more than 0.5%, 20 mL of a mixture of toluene and methanol (7:3) being used in place of methanol in the titration vessel.

Residual solvents 467: meets the requirements.

Assay for nystatin— Proceed as directed for nystatin under Antibiotics—Microbial Assays 81, blending a suitable, accurately weighed portion of Ointment in a high-speed blender for 3 to 5 minutes 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 400 USP Nystatin Units per mL. Dilute an accurately measured volume of this stock solution quantitatively with Buffer No. 6 to obtain a Test Dilution having a concentration of nystatin assumed to be equal to the median dose level of the Standard.

Assay for neomycin— Proceed with Ointment as directed in the Assay under Neomycin Sulfate Ointment.

Assay for gramicidin— Proceed as directed for gramicidin under Antibiotics—Microbial Assays 81, using an accurately weighed portion of Ointment dissolved in 50 mL of hexanes in a separator, and extracted with four 20-mL portions of 80% alcohol. Combine the extracts in a suitable volumetric flask, dilute with alcohol to volume, and mix. Dilute an accurately measured volume of the solution so obtained quantitatively and stepwise with alcohol to obtain a Test Dilution having a concentration of gramicidin assumed to be equal to the median dose level of the Standard.

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

Expert Committee : (MDANT05) Monograph Development-Antibiotics

USP29–NF24 Page 1570

Phone Number : 1-301-816-8223