Neomycin Sulfate and Gramicidin Ointment
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This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition
Issued and maintained by the United States Pharmacopeial Convention (USP)
Neomycin Sulfate and Gramicidin Ointment contains the equivalent of not less than 90.0 percent and not more than 140.0 percent of the labeled amounts of neomycin and gramicidin.
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 DETERMINATION, Method | (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.
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.
