Docusate Sodium Syrup
»Docusate Sodium Syrup contains not less than 90.0percent and not more than 110.0percent of the labeled amount of C20H37NaO7S.
Packaging and storage— Preserve in tight,light-resistant containers.
Identification— Dilute a volume of Syrup,equivalent to about 10mg of docusate sodium,with isopropyl alcohol to obtain a preparation containing about 2mg per mL,and mix.Apply,with the aid of a stream of nitrogen,50µLof the upper layer of this preparation and 50µLof an isopropyl alcohol solution of USP Docusate Sodium RScontaining about 2mg 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 two-phase solvent system consisting of ethyl acetate,water,alcohol,and ammonium hydroxide (25:20:10:1)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.Expose the plate to iodine vapors in a closed chamber for about 30minutes,and locate the spots:the test preparation produces a spot at the same RFvalue and of approximately the same size as that obtained from the Standard solution.
pHá791ñ: between 5.5and 6.5.
Assay—
Standard preparation— Transfer about 100mg of USP Docusate Sodium RS,accurately weighed,to a 100-mLvolumetric flask,dissolve in 2.5mLof alcohol,dilute with water to volume,and mix.Transfer 10.0mLof this solution to a 1000-mLvolumetric flask,dilute with water to volume,and mix.The concentration of USP Docusate Sodium RSin the Standard preparationis about 10µg per mL.
Assay preparation— Transfer an accurately measured volume of Syrup,equivalent to about 100mg of docusate sodium,to a 1000-mLvolumetric flask,allowing the pipet to drain for 15minutes.Dilute with water to volume,and mix.Transfer 10.0mLof the solution to a 100-mLvolumetric flask,dilute with water to volume,and mix.
Procedure— Transfer 20.0mLeach of the Standard preparationand of the Assay preparationto individual separators,and place 20mLof water in a third separator to provide the blank.To each separator add 5drops of hydrochloric acid,mix by swirling,add 1.0mLof methylene blue solution (1in 1000),and mix by swirling.To each separator add 20.0mLof chloroform,and shake vigorously for 5minutes.Wash each chloroform solution,in clean separators,with 20mLof water,shaking vigorously for 60seconds.Discard the washings,and filter each chloroform solution through a layer of 3g of anhydrous granular sodium sulfate,supported on glass wool,into a 100-mLvolumetric flask,washing each separator with two 10-mLportions of chloroform and filtering the washings into each flask.Dilute each flask with chloroform to volume,and mix.Concomitantly determine the absorbances of the solutions in 1-cm cells at the wavelength of maximum absorbance at about 650nm,with a suitable spectrophotometer,using the blank to set the instrument.Calculate the quantity,in mg,of C20H37NaO7Sin each mLof Syrup taken by the formula:
(10C/V)(AU/AS),
in which Cis the concentration,in µg per mL,calculated on the anhydrous basis,of USP Docusate Sodium RSin the Standard preparation;Vis the volume,in mL,of Syrup taken;and AUand ASare the absorbances of the solutions from the Assay preparationand the Standard preparation,respectively.
Auxiliary Information— Staff Liaison:Elena Gonikberg,Ph.D.,Scientist
Expert Committee:(PA4)Pharmaceutical Analysis 4
USP28–NF23Page 687
Phone Number:1-301-816-8251