Glycerin Suppositories
»Glycerin Suppositories contain Glycerin solidified with Sodium Stearate.[NOTE—If preferred,the Sodium Stearate for Glycerin Suppositories may be prepared during the making of the Suppositories by the direct reaction between Stearic Acid and Sodium Bicarbonate,Sodium Carbonate,or Sodium Hydroxide,these being taken in the correct proportion.]Glycerin Suppositories contain not less than 75.0percent and not more than 90.0percent,by weight,of glycerin (C3H8O3).
Packaging and storage— Preserve in well-closed containers.
Identification—
A: Dissolve 1g of sodium borate in 100mLof water,add 25drops of phenolphthalein TS,and mix.To a test tube containing 0.5mLof this solution add 2drops of 1Suppository that has been melted:the pink solution becomes colorless,and when it is heated the pink color reappears.
B: Disperse 12Suppositories in about 125mLof water in a 250-mLbeaker on a hot plate.Cool,add 1.5mLof hydrochloric acid,and pour the mixture into a 250-mLseparator.Extract with 75mLof hexanes,discarding the lower aqueous layer and collecting the organic layer in a beaker.Evaporate with the aid of a steam bath to near dryness:the IRabsorption spectrum of a mineral oil dispersion of the residue so obtained exhibits maxima only at the same wavelengths as those of a mineral oil dispersion of USP Stearic Acid RS.
Water,Method Iá921ñ: not more than 15.0%.
Assay— Transfer an accurately weighed quantity of Suppositories,equivalent to about 250mg of glycerin,to a 250-mLvolumetric flask.Dissolve in water,dilute with water to volume,and mix.Pipet 5mLof this solution into a 250-mLconical flask,and add 50.0mLof a reagent prepared by mixing 40mLof dilute sulfuric acid (1in 20)with 60mLof potassium periodate solution (1in 1000)acidified with 3to 5drops of sulfuric acid.Heat the solution on a steam bath for 15minutes,cool to room temperature,and add 1g of potassium iodide.Allow the flask to stand for 5minutes,and titrate with 0.02Nsodium thiosulfate VS,adding 3mLof starch TSas the endpoint is approached.Perform a blank determination,using water in place of Suppositories,and note the difference in volumes required.Each mLof the difference in volume of 0.02Nsodium thiosulfate consumed is equivalent to 0.4604mg of glycerin (C3H8O3).
Auxiliary Information— Staff Liaison:Elena Gonikberg,Ph.D.,Scientist
Expert Committee:(PA4)Pharmaceutical Analysis 4
USP28–NF23Page 912
Phone Number:1-301-816-8251