Theophylline Sodium Glycinate Tablets »Theophylline Sodium Glycinate Tablets contain an amount of theophylline sodium glycinate equivalent to not less than 93.0percent and not more than 107.0percent of the labeled amount of anhydrous theophylline (C7H8N4O2). Packaging and storage— Preserve in well-closed containers. Labeling— Label the Tablets to state both the content of theophylline sodium glycinate and the content of anhydrous theophylline. USP Reference standards á11ñ USP Theophylline RS. Identification— Triturate a quantity of finely powdered Tablets,equivalent to about 500mg of theophylline,with 10-mLand 15-mLportions of solvent hexane,and discard the solvent hexane.Triturate the residue with two 10-mLportions of a mixture of equal volumes of 6Nammonium hydroxide and water,and filter each time.Evaporate the combined filtrates to about 5mL,neutralize,if necessary,with 6Nacetic acid,using litmus,and cool to about 15,with stirring.Collect the precipitate on a filter,wash it with cold water,and dry at 105for 1hour:the theophylline so obtained melts between 270and 274,the procedure for Class Ibeing used (see Melting Range or Temperature á741ñ),and responds to Identificationtest Bunder Theophylline Sodium Glycinate. Dissolution á711ñ Medium: water;900mL. Apparatus 1: 100rpm. Time: 45minutes. Procedure— Determine the amount of anhydrous theophylline (C7H8N4O2)dissolved from UVabsorbances at the wavelength of maximum absorbance at about 272nm of filtered portions of the solution under test,suitably diluted with Dissolution Medium,if necessary,in comparison with a Standard solution having a known concentration of USP Theophylline RSin the same medium. Tolerances— Not less than 75%(Q)of the labeled amount of anhydrous C7H8N4O2is dissolved in 45minutes. Uniformity of dosage units á905ñ: meet the requirements. Assay— Place 20Tablets in a 200-mLvolumetric flask,add 50mLof water,and when the tablets have disintegrated add 50mLof 6Nammonium hydroxide.Shake until no more dissolves,then dilute with water to volume,mix,and filter through a dry filter into a dry flask,discarding the first 20mLof the filtrate.Transfer an accurately measured aliquot of the subsequent filtrate,equivalent to about 250mg of theophylline,to a 250-mLconical flask,add 20.0mLof 0.1Nsilver nitrate VS,and heat on a steam bath for 15minutes.Filter through a filter crucible under reduced pressure,and wash the precipitate with three 10-mLportions of water.Acidify the combined filtrate and washings with nitric acid,and add an excess of 3mLof the acid.Cool,add 2mLof ferric ammonium sulfate TS,and titrate the excess silver nitrate with 0.1Nammonium thiocyanate VS.Each mLof 0.1Nsilver nitrate is equivalent to 18.02mg of C7H8N4O2. Auxiliary Information— Staff Liaison:Karen A Russo,Ph.D.,Scientist Expert Committee:(PA1)Pharmaceutical Analysis 1 USP28–NF23Page 1904 Phone Number:1-301-816-8379