Estradiol Valerate
C23H32O3
356.50
Estra-1,3,5(10)-triene-3,17-diol(17b)-,17-pentanoate.
Estradiol 17-valerate. [979-32-8].
»Estradiol Valerate contains not less than 98.0percent and not more than 102.0percent of C23H32O3.
Packaging and storage—
Preserve in tight,light-resistant containers.
Identification,
Infrared Absorption á197Kñ.
Specific rotation á781Sñ:
between +41
and +47.
and +47.
Test solution:
25mg,uncorrected for moisture,per mL,in dioxane.
Water,Method Iá921ñ:
not more than 0.1%.
Limit of estradiol—
Apply 5µLof a solution of Estradiol Valerate in acetone,containing 5mg per mL,and 5µLof a solution of estradiol in acetone,containing 50µg per mL,about 2.5cm from the lower edge of a thin-layer chromatographic plate (see Chromatography á621ñ)coated with a 0.25-mm layer of chromatographic silica gel.Develop the chromatogram in a solvent system consisting of a mixture of cyclohexane and ethyl acetate (7:3)in an unlined chamber until the solvent front has moved about 15cm above the point of application.Remove the plate,dry at 90for 30minutes,and spray the plate lightly with a 3in 10solution of methanol in sulfuric acid,prepared by cautiously adding sulfuric acid to 30mLof methanol in a 100-mLvolumetric flask,in an ice bath,to volume.Heat the plate at 90for 30minutes:any spot in the chromatogram of Estradiol Valerate close to the origin and corresponding to the estradiol spot is not larger nor more intense than that produced by the standard.(The limit is 1.0%of estradiol.)
for 30minutes,and spray the plate lightly with a 3in 10solution of methanol in sulfuric acid,prepared by cautiously adding sulfuric acid to 30mLof methanol in a 100-mLvolumetric flask,in an ice bath,to volume.Heat the plate at 90for 30minutes:any spot in the chromatogram of Estradiol Valerate close to the origin and corresponding to the estradiol spot is not larger nor more intense than that produced by the standard.(The limit is 1.0%of estradiol.)
Free acid—
Neutralize 25mLof alcohol,in a conical flask,with 0.01Nsodium hydroxide VSto a faint blue color,using bromothymol blue TS.Accurately weigh 500mg of Estradiol Valerate,and dissolve it in the neutralized alcohol.Titrate rapidly with 0.01Nsodium hydroxide VSto a faint blue color.Each mLof 0.01Nsodium hydroxide is equivalent to 1.021mg of valeric acid.The free acid content,expressed as valeric acid,does not exceed 0.5%.
Ordinary impurities á466ñ—
Test solution:
acetone.
Standard solution:
acetone.
Eluant:
a mixture of cyclohexane and ether (4:1).
Visualization:
5followed by 1.
Assay—
Mobile phase—
Dissolve 0.8g of ammonium nitrate in 300mLof water,add 700mLof acetonitrile,and mix.Filter,and degas.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).
Internal standard solution—
Prepare a solution of testosterone benzoate in tetrahydrofuran having a concentration of about 2.0mg per mL.
Standard preparation—
Dissolve an accurately weighed quantity of USP Estradiol Valerate RSin Internal standard solution,and dilute quantitatively with Internal standard solutionto obtain a solution having a known concentration of about 1mg of USP Estradiol Valerate RSper mL.
Assay preparation—
Transfer about 25mg of Estradiol Valerate,accurately weighed,to a 25-mLvolumetric flask,add Internal standard solutionto volume,and mix.
Chromatographic system
(see Chromatography á621ñ)—The liquid chromatograph is equipped with a 280-nm detector and a 4-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 relative retention times are about 1.2for testosterone benzoate and 1.0for estradiol valerate;the column efficiency determined from the analyte peak is not less than 1100theoretical plates;the resolution,R,between the analyte and internal standard peaks is not less than 3.0;and the relative standard deviation for replicate injections is not more than 1.5%.
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.Calculate the quantity,in mg,of C23H32O3in the portion of Estradiol Valerate taken by the formula:
25C(RU/RS),
in which Cis the concentration,in mg per mL,of USP Estradiol 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 775
Phone Number:1-301-816-8139