Betamethasone Sodium Phosphate Injection
»Betamethasone Sodium Phosphate Injection is a sterile solution of Betamethasone Sodium Phosphate in Water for Injection.It contains an amount of betamethasone sodium phosphate (C22H28FNa2O8P)equivalent to not less than 90.0percent and not more than 110.0percent of the labeled amount of betamethasone (C22H29FO5).
Packaging and storage— Preserve in single-dose or in multiple-dose containers,preferably of Type Iglass.
Identification— Dilute the Injection with methanol,if necessary,to obtain a solution containing about 2mg of betamethasone sodium phosphate per mL.Separately apply 10µLof this test solution and 10µLof a solution of USP Betamethasone Sodium Phosphate RSin methanol containing 2mg per mLto a thin-layer chromatographic plate (see Chromatography á621ñ)coated with chromatographic silica gel mixture.Develop the chromatogram in an equilibrated chamber containing n-butyl alcohol previously shaken with 1Nhydrochloric acid,until the solvent front has moved about three-fourths of the length of the plate.Remove the plate from the developing chamber,air-dry,then spray with a mixture of sulfuric acid,methanol,and nitric acid (10:10:1).Heat the plate at 105for 10minutes:the RFvalue of the principal spot from the test solution corresponds to that obtained from the Standard solution.
Bacterial endotoxins á85ñ— It contains not more than 29.2USP Endotoxin Units per mg of betamethasone.
pHá791ñ: between 8.0and 9.0.
Particulate matter á788ñ: meets the requirements for small-volume injections.
Other requirements— It meets the requirements under Injections á1ñ.
Assay—
Mobile phase— Prepare a filtered and degassed mixture of methanol and 0.05Mmonobasic potassium phosphate (1:1).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).
Internal standard solution— Transfer about 100mg of butylparaben to a 100-mLvolumetric flask,add methanol to volume,and mix.
Standard preparation— Using an accurately weighed quantity of USP Betamethasone Sodium Phosphate RS,prepare a solution in water containing 4mg per mL.Transfer 3.0mLof this solution to a 25-mLvolumetric flask,add 5.0mLof Internal standard solution,dilute with water to volume,and mix to obtain a solution having a known concentration of about 0.5mg of USP Betamethasone Sodium Phosphate RSper mL.
Assay preparation— Transfer an accurately measured volume of Injection,equivalent to about 9mg of betamethasone,to a 25-mLvolumetric flask.Add 5.0mLof the Internal standard solution,dilute with water to volume,and mix.
Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 254-nm detector and a 3.9-mm ×30-cm column that contains packing L1.The flow rate is about 2mLper minute.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the resolution,R,between the analyte and internal standard peaks is not less than 5;and the relative standard deviation for replicate injections is not more than 2.0%.
Procedure— Separately inject equal volumes (about 20µL)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 2.4for butylparaben and 1.0for betamethasone sodium phosphate.Calculate the quantity,in mg,of C22H29FO5in each mLof the Injection taken by the formula:
(392.47/516.41)(25C/V)(RU/RS),
in which 392.47and 516.41are the molecular weights of betamethasone and betamethasone sodium phosphate,respectively;Cis the concentration,in mg per mL,of USP Betamethasone Sodium Phosphate RSin the Standard preparation;Vis the volume,in mL,of Injection taken;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 250
Phone Number:1-301-816-8139