Desoximetasone Gel

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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1 DEFINITION

Desoximetasone Gel contains NLT 90.0% and NMT 110.0% of the labeled amount of desoximetasone (C₂₂H₂₉FO₄).

2 IDENTIFICATION

A. The retention time of the desoximetasone peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

3.1 PROCEDURE

Mobile phase: Methanol, glacial acetic acid, and water (65:1:35). Adjust the ratio, if necessary, so that the retention time of desoximetasone is about 8 min.

Diluent: 15 mg/mL of calcium chloride in methanol

Standard stock solution: 0.5 mg/mL of USP Desoximetasone RS in methanol

Standard solution: 0.025 mg/mL of USP Desoximetasone RS from the Standard stock solution in Diluent

Sample solution: Nominally 0.025 mg/mL of desoximetasone in Diluent prepared as follows. Transfer an adequate amount of Gel to a suitable volumetric flask. Add about 60% of the flask volume of Diluent and sonicate to disperse the Gel. Dilute with Diluent to volume and centrifuge. Use the clear supernatant.

3.1.1 Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 254 nm

Column: 3.9-mm x 30-cm; packing L1

Flow rate: 1.5 mL/min

Injection volume: 10 µL

3.1.2 System suitability

Sample: Standard solution

3.1.3 Suitability requirements

Relative standard deviation: NMT 2.0%

3.1.4 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of desoximetasone (C₂₂H₂₉FO₄) in the portion of Gel taken:

                Result = (r_U/r_S) x (C_S/C_U) × 100

r_U = peak response of desoximetasone from the Sample solution

r_S = peak response of desoximetasone from the Standard solution

C_S = concentration of USP Desoximetasone RS in the Standard solution (mg/mL)

C_U = nominal concentration of desoximetasone in the Sample solution (mg/mL) Cu

Acceptance criteria: 90.0%-110.0%

4 OTHER COMPONENTS

4.1 ALCOHOL CONTENT

Sample solution: 50 mg/mL of Gel in methanol

Analysis: Determine the alcohol content of the Sample solution by proceeding as directed in Alcohol Determination (611), Method II-Gas Chromatographic Method, using isopropyl alcohol as the internal standard and methanol in place of water as the solvent.

Acceptance criteria: 18.0%-24.0% (w/w)

5 PERFORMANCE TESTS

MINIMUM FILL (755): Meets the requirements

6 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in collapsible tubes, at controlled room temperature.

USP REFERENCE STANDARDS (11)

USP Desoximetasone RS