Betamethasone Valerate Cream
»Betamethasone Valerate Cream contains an amount of betamethasone valerate (C27H37FO6)equivalent to not less than 90.0percent and not more than 110.0percent of the labeled amount of betamethasone (C22H29FO5),in a suitable cream base.
Packaging and storage— Preserve in collapsible tubes or in tight containers.
Identification— Transfer an amount of Cream,equivalent to about 2mg of betamethasone,to a separator,add 20mLof water and 2mLof dilute hydrochloric acid (1in 120),and mix.Extract with four 50-mLportions of chloroform,and combine the extracts.Filter through a cotton pledget,previously layered over with anhydrous sodium sulfate.Evaporate the filtrates on a steam bath under a stream of dry nitrogen to dryness.Dissolve the residue in alcohol to obtain a solution containing about 1mg per mL.Proceed as directed in Identificationtest Bunder Betamethasone Valerate,beginning with “Apply 10µLof this solution.”
Microbial limits á61ñ— It meets the requirements of the tests for absence of Staphylococcus aureusand Pseudomonas aeruginosa.
Minimum fill á755ñ: meets the requirements.
Assay—
Mobile phase ,Internal standard solution,Standard preparation,and Chromatographic system—Proceed as directed in the Assayunder Betamethasone Valerate.
Assay preparation— Transfer an accurately weighed portion of Cream,equivalent to about 2.5mg of betamethasone,to a 50-mLcentrifuge tube.Add 10.0mLof the Internal standard solutionand 5.0mLof a 1in 1000solution of glacial acetic acid in methanol.Insert the stopper into the tube,and place in a water bath held at 60until the specimen melts.Remove from the bath,and shake vigorously until the specimen resolidifies.Repeat the heating and shaking two more times.Place the tube in an ice-methanol bath for 20minutes,then centrifuge to separate the phases.Decant the clear supernatant into a suitable stoppered flask,and allow to warm to room temperature.
Procedure— Proceed as directed for Procedurein the Assayunder Betamethasone Valerate.Calculate the quantity,in mg,of C22H29FO5in the portion of Cream taken by the formula:
(392.46/476.59)(15C)(RU/RS),
in which 392.46and 476.59are the molecular weights of betamethasone and betamethasone valerate,respectively;Cis the concentration,in mg per mL,of USP Betamethasone Valerate RSin the Standard preparation;and RUand RSare the peak response ratios 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 252
Phone Number:1-301-816-8139