Neomycin Sulfate and Fluorometholone Ointment

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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Neomycin Sulfate and Fluorometholone Ointment contains the equivalent of not less than 90.0 percent and not more than 135.0 percent of the labeled amount of neomycin, and not less than 90.0 percent and not more than 110.0 percent of the labeled amount of fluorometholone (C₂₂H₂₉FO₄).

1 Packaging and storage

Preserve in collapsible tubes or in well-closed containers.

1.1 USP Reference standards 〈11〉

USP Fluorometholone RS

USP Neomycin Sulfate RS

2 Identification

A: It meets the requirements for neomycin under Thin-Layer Chromatographic Identification Test 〈201BNP〉.

B: The ratios of the retention time of the main peak to that of the internal standard peak obtained from the Standard preparation and the Assay preparation as directed in the Assay for fluorometholone do not differ by more than 2.0%.

Minimum fill 〈755〉: meets the requirements.

Water Determination, 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.

3 Assay for neomycin

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

4 Assay for fluorometholone

Internal standard solution, Mobile solvent, and Standard preparation-Prepare as directed in the Assay under Fluorometholone Cream.

Assay preparation-Transfer an accurately weighed quantity of Ointment, equivalent to about 1 mg of fluorometholone, to a suitable container, add 20.0 mL of Internal standard solution, and mix.

Procedure-Treat 20.0 mL each of the Standard preparation and the Assay preparation in the following manner. To each add 10.0 mL of hexane, shake for about 15 minutes, then allow the layers to separate, and centrifuge, if necessary. Using the lower (acetonitrile) layer, proceed as directed for Procedure in the Assay under Fluorometholone Cream, beginning with “Using a suitable microsyringe.” Calculate the quantity, in mg, of C₂₂H₂₉FO₄ in the portion of Ointment taken by the formula:

20C(Rᵤ/Rₛ)

in which the terms are as defined therein.