Fluocinolone Acetonide 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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>> Fluocinolone Acetonide Ointment contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of C₂₄H₃₀F₂O₆.

1 Packaging and storage

Preserve in collapsible tubes or tight containers.

2 USP REFERENCE STANDARDS (11)

USP Fluocinolone Acetonide RS

USP Norethindrone RS

3 Identification

Evaporate 10.0 mL of the Assay preparation obtained in the Assay to dryness, and dissolve the residue in 1 mL of chloroform: it responds to the Thin-layer Chromatographic Identification Test (201), 50 µL of the test solution and 50 µL of the Standard solution, containing about 50 µg per mL of USP Fluocinolone Acetonide RS, being applied and a mixture of chloroform and diethylamine (2:1) being used for development.

3.1 MICROBIAL ENUMERATION TESTS (61) and TESTS FOR SPECIFIED MICROORGANISMS (62)

It meets the requirements of the tests for absence of Staphylococcus aureus and Pseudomonas aeruginosa.

3.2 MINIMUM FILL (755)

Meets the requirements.

4 Assay

4.1 Internal standard solution

Dissolve a suitable quantity of USP Norethindrone RS in methanol to obtain a solution containing about 850 µg per mL.

4.2 Diluted internal standard solution

Transfer 5.0 mL of Internal standard solution to a 250-mL flask. Dilute with methanol to volume, and mix.

4.3 Standard preparation

Dissolve an accurately weighed quantity of USP Fluocinolone Acetonide RS in acetonitrile to obtain a solution having a known concentration of about 200 µg per mL. Transfer 10.0 mL of this solution and 2.0 mL of Internal standard solution to a 100-mL volumetric flask. Dilute with methanol to volume, and mix. The concentration of USP Fluocinolone Acetonide RS in the Standard preparation is 20 µg per mL.

4.4 Mobile solvent

Prepare a mixture of acetonitrile and water (1:1). Adjust the ratio as necessary to obtain suitable chromatographic performance.

4.5 Assay preparation

Transfer an accurately weighed portion of Ointment, equivalent to about 0.7 mg of fluocinolone acetonide, to a 50-mL, round-bottom centrifuge tube. Add 35.0 mL of Diluted internal standard solution, emulsify using an ultrasonic probe, and centrifuge to bring the insoluble matter to the bottom. The clear supernatant is the Assay preparation.

4.6 Apparatus

Use a suitable high-pressure liquid chromatograph (see Chromatography (621)) of the general type equipped with a detector for monitoring UV absorbance at about 254 nm, and capable of providing a flow rate of about 2 mL per minute for the Mobile solvent. Use a 50-cm x 4-mm column that contains packing L1 so as to provide a resolution factor, R (see Chromatography (621)), of at least 2.0 between peaks for norethindrone and fluocinolone acetonide. Three replicate injections of the Standard preparation show a relative standard deviation of not more than 1.5%.

4.7 Procedure

Chromatograph equal volumes of the Assay preparation and the Standard preparation, adjusting the system as necessary to obtain peaks of between about 50% and 90% of full-scale. Calculate the quantity, in mg, of C₂₄H₃₀F₂O₆ in the portion of Ointment taken by the formula:

0.035C(R_U/R_S)

in which C is the concentration, in µg per mL, of USP Fluocinolone Acetonide RS in the Standard preparation; and R_U and R_S are the ratios of the peak areas of fluocinolone acetonide and the internal standard obtained from the Assay preparation and the Standard preparation, respectively.