Clobetasol Propionate Ointment
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).
• A. Thin-Layer Chromatographic Identification Test 201
Standard solution: 0.5 mg/mL of 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 RF value of the principal spot obtained from the Test solution corresponds to that from the Standard solution.
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: Dissolve a quantity of USP Clobetasol Propionate RS in methanol and Internal standard solution to obtain a final solution of 0.04 mg/mL of USP Clobetasol Propionate RS and 0.08 mg/mL of beclomethasone dipropionate
Sample solution: Nominally 0.04 mg/mL of clobetasol propionate. Transfer a portion of Ointment equivalent to 1.0 mg of clobetasol propionate into a 125-mL separatory funnel. Add 30 mL of hexane, 10.0 mL of the Internal standard solution, and shake. Collect the lower layer in a 25-mL volumetric flask. Extract the hexane remaining in the separatory funnel with two 5-mL portions of Mobile phase, and combine all of the extracts in the 25-mL volumetric flask. Dilute with Mobile phase to volume, and pass a portion through a filter of 0.45-µm pore size.
Detector: UV 240 nm
Column: 4.6-mm × 15-cm; packing L1
Flow rate: 1 mL/min
Injection size: 10 µL
Sample: System suitability solution
[NoteThe relative retention times for clobetasol propionate and clobetasol propionate related compound A are 1.0 and 1.1, respectively. ]
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
Samples: Standard solution and Sample solution
[NoteThe 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 Ointment taken:
Result = (RU/RS) × (CS/CU) × 100
Acceptance criteria: 90.0%115.0%
• 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
• Packaging and Storage: Preserve in collapsible tubes or in tight containers. Store at controlled room temperature. Do not refrigerate.
• USP Reference Standards 11
Auxiliary Information Please check for your question in the FAQs before contacting USP.
USP35NF30 Page 2715