Docusate Sodium
C20H37NaO7S
444.56
Butanedioic acid,sulfo-,1,4-bis(2-ethylhexyl)ester,sodium salt.
Sodium 1,4-bis(2-ethylhexyl)sulfosuccinate [577-11-7].
»Docusate Sodium contains not less than 99.0percent and not more than 100.5percent of C20H37NaO7S,calculated on the anhydrous basis.
Packaging and storage—
Preserve in well-closed containers.
Clarity of solution—
Dissolve 25g in 100mLof alcohol:the solution does not develop a haze within 24hours.
Identification—
Place a small piece of it on a salt plate,add 1drop of acetone,and promptly cover with another salt plate.Rub the plates together to dissolve the specimen,slide the plates apart,and allow the acetone to evaporate:the IRabsorption spectrum of the film so obtained exhibits maxima only at the same wavelengths as that of a similar preparation of USP Docusate Sodium RS.
Water,Method Iá921ñ:
not more than 2.0%.
Residue on ignition á281ñ:
between 15.5%and 16.5%,calculated on the anhydrous basis.
Heavy metals á231ñ—
Transfer 2.0g to a platinum crucible,and ignite until free from carbon.Cool,moisten the residue with 1mLof hydrochloric acid,and evaporate on a steam bath to dryness.Add 2mLof 6Nacetic acid,digest on a steam bath for 5minutes,filter into one of a pair of matched 50-mLcolor-comparison tubes,and wash the residue with sufficient water to make 25mL:the limit is 0.001%.
Limit of bis(2-ethylhexyl)maleate—
Place 12.5g of Docusate Sodium,previously dried at 105
for 2hours and accurately weighed,in a 100-mLvolumetric flask.Pipet 20mLof pH10alkaline borate buffer (see under Solutionsin the section Reagents,Indicators,and Solutions)into the flask,and add about 70mLof alcohol.Swirl the flask and contents,with gentle warming,until the solid dissolves.Cool,and add alcohol to volume.Transfer a portion of this test solution to a polarographic cell that is immersed in a water bath regulated at 25±0.5,and deaerate by bubbling through the solution,for 10minutes,purified nitrogen that previously has been passed through a solution prepared by mixing 4volumes of alcohol and 1volume of water.Insert the dropping mercury electrode of a suitable polarograph,and record the polarogram from -0.5volt to -1.6volts,using a saturated calomel electrode as the reference electrode (see Polarography á801ñ).Determine the height of the diffusion current at the current plateau at about -1.45volts.To a separate 50-mLportion of the solution add 25mg of USP Bis(2-ethylhexyl)maleate RS,accurately weighed,and when solution is complete,deaerate a portion of the resulting solution,and record the polarogram,as directed in the foregoing.The diffusion current for the test solution of Docusate Sodium is not greater than one-half the diffusion current of the solution containing the added USP Bis(2-ethylhexyl)maleate RS[not more than 0.4%of bis(2-ethylhexyl)maleate].
for 2hours and accurately weighed,in a 100-mLvolumetric flask.Pipet 20mLof pH10alkaline borate buffer (see under Solutionsin the section Reagents,Indicators,and Solutions)into the flask,and add about 70mLof alcohol.Swirl the flask and contents,with gentle warming,until the solid dissolves.Cool,and add alcohol to volume.Transfer a portion of this test solution to a polarographic cell that is immersed in a water bath regulated at 25±0.5,and deaerate by bubbling through the solution,for 10minutes,purified nitrogen that previously has been passed through a solution prepared by mixing 4volumes of alcohol and 1volume of water.Insert the dropping mercury electrode of a suitable polarograph,and record the polarogram from -0.5volt to -1.6volts,using a saturated calomel electrode as the reference electrode (see Polarography á801ñ).Determine the height of the diffusion current at the current plateau at about -1.45volts.To a separate 50-mLportion of the solution add 25mg of USP Bis(2-ethylhexyl)maleate RS,accurately weighed,and when solution is complete,deaerate a portion of the resulting solution,and record the polarogram,as directed in the foregoing.The diffusion current for the test solution of Docusate Sodium is not greater than one-half the diffusion current of the solution containing the added USP Bis(2-ethylhexyl)maleate RS[not more than 0.4%of bis(2-ethylhexyl)maleate].
Assay—
Tetra-n-butylammonium iodide solution—
Transfer 1.250g of tetra-n-butylammonium iodide to a 500-mLvolumetric flask,dilute with water to volume,and mix.
Salt solution—
Transfer 100g of anhydrous sodium sulfate and 10g of sodium carbonate to a 400-mLbeaker,and add water to dissolve the two salts.Transfer the solution to a 1000-mLvolumetric flask,dilute with water to volume,and mix.
Procedure—
Dissolve about 50mg of Docusate Sodium,accurately weighed,in 50mLof chloroform in a glass-stoppered,250-mLconical flask.Add 50mLof Salt solutionand 0.5mLof bromophenol blue TS,and mix.Titrate with Tetra-n-butylammonium iodide solutionuntil about 1mLfrom the endpoint,and shake the stoppered flask vigorously for about 2minutes.Continue the titration in 2-drop increments,shaking vigorously for about 10seconds after each addition,and then allow the flask to stand about 10seconds.Continue the titration until the chloroform layer just assumes a blue color.Each mLof Tetra-n-butylammonium iodide solutionis equivalent to 3.009mg of C20H37NaO7S.
Auxiliary Information—
Staff Liaison:Elena Gonikberg,Ph.D.,Scientist
Expert Committee:(PA4)Pharmaceutical Analysis 4
USP28–NF23Page 685
Phone Number:1-301-816-8251