Clobetasol Propionate Ointment

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

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

DOWNLOAD PDF HERE

1 DEFINITION

Clobetasol Propionate Ointment is Clobetasol Propionate in a suitable ointment base. It contains NLT 90.0% and NMT 115.0% of the labeled amount of clobetasol propionate (C₂₅H₃₂ClFO₅).

2 IDENTIFICATION

2.1 Delete the following

A. Thin-Layer Chromatographic Identification Test 〈201〉

Standard solution: 0.5 mg/mL of USP Clobetasol Propionate RS in chloroform

Test solution: Nominally 0.5 mg/mL of clobetasol propionate. Transfer a portion of Ointment equivalent to 1.0 mg of clobetasol propionate to a 25-mL, plastic-stoppered centrifuge tube. Add 10 mL of methanol, and cap. Heat in a 70° water bath for 4 min, remove the tube from the bath, and shake vigorously. Repeat the heating and shaking. Freeze the mixture in an ice bath for 5 min, and centrifuge at about 3500 rpm for 10 min. Transfer 5 mL of the supernatant to a suitable vial. Evaporate with the aid of a stream of nitrogen to dryness. Dissolve the residue in 1.0 mL of chloroform.

Developing solvent system: Chloroform, acetone, and alcohol (100:10:5)

Acceptance criteria: The R_F value of the principal spot obtained from the Test solution corresponds to that from the Standard solution. 

2.2 Add the following

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

2.3 Add the following

B. The UV spectrum of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

Change to read:

3.1 Procedure

Buffer: 6 g/L of monobasic sodium phosphate. Adjust with phosphoric acid to a pH of 2.5.

Mobile phase: Acetonitrile, methanol, and Buffer (475:100:425)

Solution A: Absolute alcohol and methanol (95:5)

Internal standard solution: 0.06 mg/mL of USP Beclomethasone Dipropionate RS in Solution A

System suitability solution: 0.066 mg/mL of USP Clobetasol Propionate RS and 2.6 µg/mL of USP Clobetasol Propionate Related Compound A RS in Internal standard solution

Standard solution: 0.066 mg/mL of USP Clobetasol Propionate RS in Internal standard solution

Sample solution: Nominally 0.066 mg/mL of clobetasol propionate in Internal standard solution prepared as follows. Transfer a suitable amount of Ointment equivalent to 1.65 mg of clobetasol propionate to a 50-mL glass centrifuge tube with a screw cap having a Teflon liner. Pipet 25 mL of Internal standard solution, and heat in a water bath at 70° for NLT 10 min with intermittent short vortexing. After heating, mix the sample on a vortex mixer for NLT 30 s and cool in an ice bath for NLT 10 min. Repeat the heating, vortexing, and cooling cycle two more times. Allow the contents to reach room temperature for a minimum of 30 min. Pass a portion through a suitable filter of 0.45-µm pore size, discarding the first 5 mL of the filtrate.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

• Mode: LC
• Detector: UV 240 nm. For Identification B, use a diode array detector in the range of 210-350 nm.
• Column: 4.6-mm × 15-cm; 2.6-µm packing L1
• Flow rate: 1 mL/min
• Injection volume: 10 µL
• Run time: NLT 3 times the retention time of clobetasol propionate

System suitability

• Samples: System suitability solution and Standard solution
• [Note-See Table 1 for the relative retention times.]
• Suitability requirements
• Resolution: NLT 1.5 between clobetasol propionate and clobetasol propionate related compound A, System suitability solution
• Tailing factor: NMT 2.0 for both the clobetasol propionate and beclomethasone dipropionate peaks, System suitability solution
• Relative standard deviation: NMT 2.0% for the area ratio of clobetasol propionate to beclomethasone dipropionate, Standard solution

Analysis

• Samples: Standard solution and Sample solution
• Calculate the percentage of the labeled amount of clobetasol propionate (C₂₅H₃₂ClFO₅) in the portion of Ointment taken:

Result = (R_u/R_s) × (C_s/C_u) × 100

R_u = peak area ratio of clobetasol propionate to beclomethasone dipropionate from the Sample solution

R_s = peak area ratio of clobetasol propionate to beclomethasone dipropionate from the Standard solution

C_s = concentration of USP Clobetasol Propionate RS in the Standard solution (mg/mL)

C_u = nominal concentration of clobetasol propionate in the Sample solution (mg/mL)

• Acceptance criteria: 90.0%–115.0%

4 IMPURITIES

Add the following:

4.1 Organic Impurities

Buffer, Mobile phase, Solution A, Internal standard solution, System suitability solution, Standard solution, Sample solution, and Chromatographic system: Proceed as directed in the Assay.

Sensitivity solution: 0.066 µg/mL of USP Clobetasol Propionate RS in Internal standard solution

System suitability

• Samples: System suitability solution, Standard solution, and Sensitivity solution
• Suitability requirements
• Resolution: NLT 1.5 between clobetasol propionate and clobetasol propionate related compound A, System suitability solution
• Tailing factor: NMT 2.0 for the clobetasol propionate and beclomethasone dipropionate peaks, System suitability solution
• Relative standard deviation: NMT 2.0% for the area ratio of clobetasol propionate to beclomethasone dipropionate, Standard solution
• Signal-to-noise-ratio: NLT 10 for clobetasol propionate, Sensitivity solution

Analysis

Sample: Sample solution

Calculate the percentage of each degradation product in the portion of Ointment taken:

Result = (r_u/r_T) × (1/F) × 100

r_u = peak response of each individual degradation product from the Sample solution

r_T = sum of the peak responses of clobetasol propionate and all the degradation products from the Sample solution

F = relative response factor for each individual degradation product (see Table 1)

Acceptance criteria: See Table 1. The reporting threshold is 0.1%.

a: 21-Chloro-9-fluoro-11β,17-dihydroxy-16β-methylpregna-1,4-diene-3,20-dione.

b: Internal standard.

5 SPECIFIC TESTS

Microbial Enumeration Tests 〈61〉 and Tests for Specified Microorganisms 〈62〉: The total aerobic microbial count does not exceed 10² cfu/g. It meets the requirements of the tests for absence of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Salmonella species.

Minimum Fill 〈755〉: Meets the requirements

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in collapsible tubes or in tight containers. Store at controlled room temperature. Do not refrigerate.

USP Reference Standards 〈11〉

USP Beclomethasone Dipropionate RS 

USP Clobetasol Propionate RS

USP Clobetasol Propionate Related Compound A RS

(17R)-4′-Chloro-5′-ethyl-9-fluoro-11β-hydroxy-16β-methylspiro[androsta-1,4-diene-17,2′(3′H)-furan]-3,3′-dione.

C₂₅H₃₀ClFO₄ 448.96