Clobetasol Propionate Ointment
»Clobetasol Propionate Ointment is Clobetasol Propionate in a suitable ointment base.It contains not less than 90.0percent and not more than 115.0percent of the labeled amount of C25H32ClFO5.
Packaging and storage—
Preserve in collapsible tubes or in tight containers.Store at controlled room temperature (15
to 30).Do not refrigerate.
to 30).Do not refrigerate.
USP Reference standards á11ñ—
USP Clobetasol Propionate RS.USP Clobetasol Propionate Related Compound A RS.
Identification—
Transfer a quantity of Ointment,equivalent to about 1.0mg of clobetasol propionate,to a 25-mLplastic-stoppered centrifuge tube.Add 10mLof methanol,and cap.Heat in a 70water bath for about 4minutes,remove the tube from the bath,and shake vigorously.Repeat the heating and shaking.Freeze the mixture in an ice bath for about 5minutes,and centrifuge at about 3500rpm for about 10minutes.Transfer about 5mLof the supernatant to a suitable vial.Evaporate with the aid of a stream of nitrogen to dryness.Dissolve the residue in about 1.0mLof chloroform to obtain the test solution.Prepare a Standard solution of USP Clobetasol Propionate RShaving the same concentration as the test solution.The test solution so obtained responds to the Thin-Layer Chromatographic Identification Test á201ñ,a mixture of chloroform,acetone,and ethanol (100:10:5)being used as the developing solvent.
water bath for about 4minutes,remove the tube from the bath,and shake vigorously.Repeat the heating and shaking.Freeze the mixture in an ice bath for about 5minutes,and centrifuge at about 3500rpm for about 10minutes.Transfer about 5mLof the supernatant to a suitable vial.Evaporate with the aid of a stream of nitrogen to dryness.Dissolve the residue in about 1.0mLof chloroform to obtain the test solution.Prepare a Standard solution of USP Clobetasol Propionate RShaving the same concentration as the test solution.The test solution so obtained responds to the Thin-Layer Chromatographic Identification Test á201ñ,a mixture of chloroform,acetone,and ethanol (100:10:5)being used as the developing solvent.
Microbial limits á61ñ—
It meets the requirements of the tests for absence of Staphylococcus aureus,Pseudomonas aeruginosa,Escherichia coli,and Salmonellaspecies,and the total aerobic microbial count does not exceed 100cfu per g.
Minimum fill á755ñ:
meets the requirements.
Assay—
[NOTE—Where peak responses are indicated,use peak areas.]
Mobile phase,Internal standard solution,Standard preparation,System suitability solution,and Chromatographic system—
Proceed as directed in the Assayunder Clobetasol Propionate.
Assay preparation—
Transfer an accurately weighed portion of Ointment,equivalent to about 1.0mg of clobetasol propionate,to a 125-mLseparator.Add 30mLof hexane,10.0mLof Internal standard solution,and shake.Collect the lower layer in a 25-mLvolumetric flask.Extract the hexane remaining in the separator with two 5-mLportions of Mobile phase,and combine all of the extracts in the 25-mLvolumetric flask.Dilute with Mobile phaseto volume,and mix.Filter a portion through a 0.45-µm filter.
Procedure—
Separately inject equal volumes (about 10µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.The relative retention times are about 1.0for clobetasol propionate and 1.6for beclomethasone dipropionate.Calculate the quantity,in mg,of C25H32ClFO5in the portion of Ointment taken by the formula:
25C(RU/RS),
in which Cis the concentration,in mg per mL,of USP Clobetasol Propionate RSin the Standard preparation,and RUand RSare the ratios of the clobetasol propionate peak to the internal standard peak obtained from the Assay preparationand the Standard preparation,respectively.
Auxiliary Information—
Staff Liaison:Clydewyn M.Anthony,Ph.D.,Scientist
Expert Committee:(PA1)Pharmaceutical Analysis 1
USP28–NF23Page 503
Phone Number:1-301-816-8139