Clobetasol Propionate Cream
» Clobetasol Propionate Cream is Clobetasol Propionate in a suitable cream base. It contains not less than 90.0 percent and not more than 115.0 percent of the labeled amount of C25H32ClFO5.
Packaging and storage— Preserve in collapsible tubes or in tight containers. Store at controlled room temperature. Do not refrigerate.
Identification— Transfer a quantity of Cream, equivalent to about 0.75 mg of clobetasol propionate, to a 25-mL plastic-stoppered centrifuge tube. Add 10 mL of methanol, and cap. Heat in a 60 water bath for about 4 minutes, remove the tube from the bath, and shake vigorously. Repeat the heating and shaking. Cool to room temperature, add 3.5 mL of water, and mix. Centrifuge at about 3500 rpm for about 10 minutes. Transfer about 5 mL of the supernatant to a 100-mL separator, add 1 g of sodium chloride and 10 mL of water, and mix. Extract with 5 mL of chloroform by shaking for 1 minute, collect the lower layer, and evaporate with the aid of a stream of nitrogen to dryness. Dissolve the residue in about 0.5 mL of chloroform to obtain the test solution. Prepare a Standard solution of USP Clobetasol Propionate RS having the same concentration as the test solution. The test solution so obtained responds to the Thin-Layer Chromatographic Identification Test 201, a mixture of chloroform, acetone, and alcohol (100:10:5) being used as the developing solvent.
Microbial enumeration tests 61 and Tests for specified microorganisms 62— It meets the requirements of the tests for absence of Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Salmonella species, and the total aerobic microbial count does not exceed 100 cfu per g.
Minimum fill 755: meets the requirements.
pH 791: between 4.5 and 7.0.
Assay— [note—Where peak responses are indicated, use peak areas.]
Internal standard solution, Standard preparation, System suitability solution, and Chromatographic system— Proceed as directed in the Assay under Clobetasol Propionate.
Mobile phase— Prepare a filtered and degassed mixture containing acetonitrile, 0.05 M monobasic sodium phosphate (adjusted with 50% sodium hydroxide solution to a pH of 5.5), and methanol (95:85:20). Make adjustments if necessary (see System Suitability under Chromatography 621).
Assay preparation— Transfer an accurately weighed portion of Cream, equivalent to about 1.0 mg of clobetasol propionate, to a 50-mL volumetric flask. Add 10.0 mL of Internal standard solution and 15.0 mL of methanol. Shake vigorously to disperse the cream, and centrifuge at about 3500 rpm for about 10 minutes. Filter a portion of the supernatant through a 0.45-µm filter.
Procedure— Separately inject equal volumes (about 10 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. The relative retention times are about 1.0 for clobetasol propionate and 1.6 for beclomethasone dipropionate. Calculate the quantity, in mg, of C25H32ClFO5 in the portion of Cream taken by the formula:
25C(RU / RS)
in which C is the concentration, in mg per mL, of USP Clobetasol Propionate RS in the Standard preparation; and RU and RS are the ratios of the clobetasol propionate peak to the internal standard peak obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Daniel K. Bempong, Ph.D.
Senior Scientist
1-301-816-8143		 (MDPS05) Monograph Development-Pulmonary and Steroids
Reference Standards Lili Wang, Technical Services Scientist
1-301-816-8129
RSTech@usp.org
61 Radhakrishna S Tirumalai, Ph.D.
Senior Scientist
1-301-816-8339		 (MSA05) Microbiology and Sterility Assurance
62 Radhakrishna S Tirumalai, Ph.D.
Senior Scientist
1-301-816-8339		 (MSA05) Microbiology and Sterility Assurance
USP32–NF27 Page 1977
Chromatographic Column—
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.