Fluocinonide 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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>> Fluocinonide Ointment contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of fluocinonide (C₂₆H₃₂F₂O₇).

1 Packaging and storage

Preserve in collapsible tubes or tight containers.

2 USP REFERENCE STANDARDS (11)

USP Fluocinonide RS

3 Identification

Weigh an amount of Ointment, equivalent to about 2.5 mg of fluocinonide, into a glass-stoppered, 50-mL centrifuge tube containing 20 mL of cyclohexane. Gently disperse to form a suspension. Add 5 mL of water and 10 mL of methanol. Shake vigorously, allow the phases to separate, and discard the upper phase. Add 20 mL of water and 5 mL of chloroform, shake vigorously, centrifuge, and transfer a portion of the chloroform layer to a small test tube containing about 200 mg of anhydrous sodium sulfate. Mix, and allow to stand until the extract is clear. Using the clear chloroform extract as the Test preparation, proceed as directed in the Identification under Fluocinonide Cream, beginning with "Apply 10 µL of the Test solution."

MINIMUM FILL (755): meets the requirements.

4 Assay

4.1 Mobile phase

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

4.2 Standard preparation

Dissolve an accurately weighed quantity of USP Fluocinonide RS in acetonitrile to obtain a solution having a known concentration of about 400 µg per mL. Transfer 10.0 mL of this solution to a 100-mL volumetric flask. Dilute with methanol to volume, and mix. The final concentration of USP Fluocinonide RS is about 40 µg per mL.

4.3 Assay preparation

Transfer an accurately weighed quantity of Ointment, containing about 1.35 mg of fluocinonide, to a round-bottom, 50-mL centrifuge tube. Add 35.0 mL of methanol. Emulsify, using an ultrasonic probe, and centrifuge to bring the insoluble matter to the bottom. The clear supernatant is the Assay preparation.

4.4 Chromatographic system (see Chromatography (621))

Proceed as directed under Fluocinonide Cream, except that the flow rate for the Mobile phase is about 1 mL per minute.

4.5 Procedure

Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of fluocinonide (C₂₆H₃₂F₂O₇) 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 Fluocinonide RS in the Standard preparation; and r_U and r_S are the peak responses due to fluocinonide obtained from the Assay preparation and the Standard preparation, respectively.