Clobetasol Propionate Topical Solution
DEFINITION
Clobetasol Propionate Topical Solution contains NLT 90.0% and NMT 110.0% of the labeled amount of clobetasol propionate (C25H32ClFO5).
IDENTIFICATION
• A. Thin-Layer Chromatographic Identification Test 
201
201
Standard solution:
0.75 mg/mL of USP Clobetasol Propionate RS in chloroform
Test solution:
Nominally 0.75 mg/mL of clobetasol propionate. Transfer a portion of Topical Solution equivalent to 1.5 mg of clobetasol to a 50-mL separatory funnel. Add 5 mL of water, and extract with 5 mL of chloroform. Collect the lower layer through a cotton wool plug, and evaporate with the aid of a stream of nitrogen to dryness. Dissolve the residue in 2 mL of chloroform.
Developing solvent system:
Chloroform, acetone, and alcohol (100:10:5)
Acceptance criteria:
The RF value of the principal spot obtained from the Test solution corresponds to that from the Standard solution.
ASSAY
• Procedure
Buffer:
0.05 M monobasic sodium phosphate. Adjust with 85% phosphoric acid to a pH of 2.5.
Mobile phase:
Acetonitrile, methanol, and Buffer (95:20:85)
Internal standard solution:
0.2 mg/mL of beclomethasone dipropionate in methanol
System suitability solution:
0.001 mg/mL of USP Clobetasol Propionate Related Compound A RS and 0.1 mg/mL of USP Clobetasol Propionate RS in Mobile phase
Standard solution:
0.04 mg/mL of USP Clobetasol Propionate RS and 0.08 mg/mL of beclomethasone dipropionate prepared as follows. Transfer 1.0 mg of USP Clobetasol Propionate RS to a 25-mL volumetric flask, add 10.0 mL of the Internal standard solution, and dilute with methanol to volume.
Sample solution:
Nominally 0.04 mg/mL of clobetasol propionate. Transfer a portion of Topical Solution equivalent to 1.0 mg of clobetasol propionate to a 25-mL volumetric flask, add 10.0 mL of the Internal standard solution, and dilute with Mobile phase to volume.
Chromatographic system
Mode:
LC
Detector:
UV 240 nm
Column:
4.6-mm × 15-cm; packing L1
Flow rate:
1 mL/min
Injection size:
10 µL
System suitability
Sample:
System suitability solution
[Note—The relative retention times for clobetasol propionate and clobetasol propionate related compound A are 1.0 and 1.1, respectively. ]
Suitability requirements
Resolution:
NLT 1.5 between clobetasol propionate and clobetasol propionate related compound A
Column efficiency:
NLT 5000 theoretical plates for the clobetasol propionate peak
Tailing factor:
NMT 2.0 for the clobetasol propionate peak
Relative standard deviation:
NMT 2.0% for the clobetasol propionate peak
Analysis
Samples:
Standard solution and Sample solution
[Note—The relative retention times for clobetasol propionate and beclomethasone dipropionate are 1.0 and 1.6, respectively. ]
Calculate the percentage of clobetasol propionate (C25H32ClFO5) in the portion of Topical Solution taken:
Result = (RU/RS) × (CS/CU) × 100
| RU | = | = ratio of the clobetasol propionate peak area to the internal standard peak area from the Sample solution |
| RS | = | = ratio of the clobetasol propionate peak area to the Internal standard peak area from the Standard solution |
| CS | = | = concentration of USP Clobetasol Propionate RS in the Standard solution (mg/mL) |
| CU | = | = nominal concentration of clobetasol propionate in the Sample solution (mg/mL) |
Acceptance criteria:
90.0%–110.0%
PERFORMANCE TESTS
• Minimum Fill 755:
Meets the requirements
755:
Meets the requirements
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.
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.
• pH 791:
4.5–6.0
791:
4.5–6.0
ADDITIONAL REQUIREMENTS
• Packaging and Storage:
Preserve in tight containers. Store at controlled room temperature. Do not refrigerate.
• USP Reference Standards 11
11
USP Clobetasol Propionate RS 
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USP Clobetasol Propionate Related Compound A RS
9
-Fluoro-11
-hydroxy-16-methyl 3-oxo-androsta-1,4-diene-17(R)-spiro-2¢-[4¢-chloro-5¢-ethylfuran-3¢(2¢H)-one].
C25H30ClFO4 448.96
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9
-Fluoro-11-hydroxy-16-methyl 3-oxo-androsta-1,4-diene-17(R)-spiro-2¢-[4¢-chloro-5¢-ethylfuran-3¢(2¢H)-one].
C25H30ClFO4 448.96
Auxiliary Information—
Please check for your question in the FAQs before contacting USP.
| Topic/Question | Contact | Expert Committee |
|---|---|---|
| Monograph | Domenick Vicchio, Ph.D.
Senior Scientific Liaison 1-301-998-6828 |
(SM42010) Monographs - Small Molecules 4 |
| 61 |
Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison 1-301-816-8339 |
(GCM2010) General Chapters - Microbiology |
| 62 |
Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison 1-301-816-8339 |
(GCM2010) General Chapters - Microbiology |
| Reference Standards | RS Technical Services 1-301-816-8129 rstech@usp.org |
USP35–NF30 Page 2715