Packaging and storage— Preserve in collapsible tubes or in well-closed containers.

USP Reference standards 11— USP Gramicidin RS. USP Neomycin Sulfate RS.

Thin-Layer Chromatographic Identification Test 201BNP: meets the requirements.

Minimum fill 755: meets the requirements.

Water, Method I 921: not more than 1.0%, 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 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 percent alcohol. Combine the extracts in a suitable volumetric flask, dilute with alcohol to volume, and mix. Dilute this solution 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.

Expert Committee : (MDANT05) Monograph Development-Antibiotics

USP29–NF24 Page 1497

Phone Number : 1-301-816-8223