Desoximetasone Cream

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 Cream is Desoximetasone in an emollient cream base. It 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 th e Standard solution, as obtained in the Assay.

3 ASSAY

3.1 PROCEDURE

Mobile phase: Methanol, glacial acetic acid, and water (65:1:35)

Internal standard solution: 0.04 mg/mL of ethylparaben in methanol

Standard stock solution: 0.4 mg/mL of USP Desoximetasone RS in methanol

Standard solution: 0.05 mg/mL of USP Desoximetasone RS and 0.01 mg/mL of ethylparaben from the Standard stock solution and Internal standard solution, respectively, in methanol

Sample solution: Transfer an amount of Cream, nominally equivalent to 2 mg of desoximetasone, to a 50-mL centrifuge tube, and add a few 3-mm glass beads. Add 10.0 mL of Internal standard solution and 30 mL of methanol. Tightly cap the centrifuge tube, and immerse it for 10 min in a bath maintained at 65°. Remove the tube from the bath, and immediately vortex at high speed for 30 s. Return the tube to the hot water bath for 5 min, remove it from the bath, and immediately vortex for 30 s. Repeat the procedure, then cool the tube in an ice-bath held at 10° until no further flocculent precipitation occurs. Centrifuge, and use the supernatant.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 254 nm

Column: 4.6-mm x 15-cm; packing

Flow rate: 1 mL/min

Injection volume: 10 µL

3.1.1 System suitability

Sample: Standard solution

[NOTE-The relative retention times for ethylparaben and desoximetasone are about 1 and 2, respectively.]

3.1.2 Suitability requirements

Resolution: NLT 2.0 between desoximetasone and ethylparaben

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0%

3.1.3 Analysis

Samples: Standard solution and Sample solution

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

                Result = (R_U/R_S) x (C_S/C_U) × 100

R_U = peak response ratio of desoximetasone to ethylparaben from the Sample solution 

R_S = peak response ratio of desoximetasone to ethylparaben 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)

Acceptance criteria: 90.0%-110.0%

4 PERFORMANCE TESTS

MINIMUM FILL (755): Meets the requirements

5 SPECIFIC TESTS

PH (791)

Sample solution: Add 15 mL of boiling water to 3.5 g of Cream in a 50-mL centrifuge tube, cap the tube, shake vigorously until the Cream is uniformly dispersed, then place the tube in a steam bath until the water and oil layers separate completely. Cool and separate the layers.

Analysis: Determine the pH of the aqueous phase.

Acceptance criteria: 4.0-8.0

6 ADDITIONAL REQUIREMENTS

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

USP REFERENCE STANDARDS (11)

USP Desoximetasone RS