Betamethasone Valerate Lotion
»Betamethasone Valerate Lotion contains an amount of Betamethasone Valerate (C27H37FO6)equivalent to not less than 95.0percent and not more than 115.0percent of the labeled amount of betamethasone (C22H29FO5).
Packaging and storage— Preserve in tight,light-resistant containers,and store at controlled room temperature.
Identification— Mix an amount of Lotion,equivalent to about 5mg of betamethasone,with a mixture of methanol and chloroform (2:1)to make 10mL.Apply 20µLof this solution and 20µLof a Standard solution of USP Betamethasone Valerate RSin a mixture of methanol and chloroform (2:1)containing 0.6mg per mLto a suitable thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel mixture.Allow the spots to dry,and develop the chromatogram in a solvent system consisting of a mixture of chloroform and ethyl acetate (1:1),until the solvent front has moved about three-fourths of the length of the plate.Remove the plate from the developing chamber,mark the solvent front,and allow the solvent to evaporate.View the spots under UVlight:the RFvalue of the principal spot obtained from the test solution corresponds to that obtained from the Standard solution.
Microbial limits á61ñ— It meets the requirements of the tests for absence of Staphylococcus aureusand Pseudomonas aeruginosa.
Minimum fill á755ñ: meets the requirements.
pHá791ñ: between 4.0and 6.0.
Assay—
Mobile phase and Chromatographic system—Proceed as directed in the Assayunder Betamethasone Valerate.
Internal standard solution— Transfer about 50mg of beclomethasone dipropionate to a 25-mLvolumetric flask,add chloroform to volume,and mix.
Standard preparation— Transfer about 40mg of USP Betamethasone Valerate RS,accurately weighed,to a 25-mLvolumetric flask,add chloroform to volume,and mix.Pipet 2mLof this solution into a 50-mLcentrifuge tube,add 10mLof 0.1Nhydrochloric acid,then add 2.0mLof Internal standard solution.Insert the stopper into the tube,shake vigorously for about 2minutes,and centrifuge to separate the phases.Using a syringe,transfer the lower,chloroform phase to a small stoppered vial.Evaporate the chloroform on a steam bath,at low heat,with the aid of a stream of nitrogen.Add 4.0mLof a 1in 1000solution of glacial acetic acid in methanol,and swirl to dissolve the residue.
Assay preparation— Transfer an accurately weighed portion of Lotion,equivalent to about 2.5mg of betamethasone,to a stoppered,50-mLcentrifuge tube.Add 10.0mLof 0.1Nhydrochloric acid,insert the stopper,and shake to disperse the specimen.Add 2.0mLof chloroform and 2.0mLof Internal standard solution,insert the stopper,and proceed as directed for Standard preparation,beginning with “shake vigorously for about 2minutes.”
Procedure— Proceed as directed for Procedurein the Assayunder Betamethasone Valerate.Calculate the quantity,in mg,of betamethasone (C22H29FO5)in the portion of Lotion taken by the formula:
(392.46/476.59)(4C)(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
Pharmacopeial Forum:Volume No.30(2)Page 461
Phone Number:1-301-816-8139