Aminophylline Rectal Solution
»Aminophylline Rectal Solution is an aqueous solution of Aminophylline,prepared with the aid of Ethylenediamine.It contains an amount of aminophylline equivalent to not less than 90.0percent and not more than 110.0percent of the labeled amount of anhydrous theophylline (C7H8N4O2).
Aminophylline Rectal Solution may contain an excess of ethylenediamine,but no other substance may be added for the purpose of pHadjustment.
Packaging and storage— Preserve in tight,single-dose or multiple-dose containers,at controlled room temperature.
Labeling— Label the Rectal Solution to state the content of anhydrous theophylline.
Identification— Dilute a volume of Rectal Solution,equivalent to about 500mg of aminophylline,with water to about 20mL,and add,with constant stirring,1mLof 3Nhydrochloric acid or sufficient to precipitate the theophylline completely.Filter,wash with small portions of cold water until free from chloride,and dry at 105for 4hours.Use the precipitate and the filtrate for the following tests.
A: Infrared Absorption á197Kñ.
B: The filtrate obtained as directed above meets the requirements for Identificationtest Cunder Aminophylline.
pHá791ñ: between 9.0and 9.5.
Ethylenediamine content— Measure accurately a volume of Rectal Solution,equivalent to about 500mg of aminophylline,and dilute with water,if necessary,to make about 30mL.Add methyl orange TS,and titrate with 0.1Nhydrochloric acid VS.Each mLof 0.1Nhydrochloric acid is equivalent to 3.005mg of C2H8N2.The Rectal Solution contains between 218mg and 267mg of ethylenediamine (C2H8N2)per g of anhydrous theophylline (C7H8N4O2)found in the Assay.
Assay—
Standard preparation— Dissolve an accurately weighed quantity of USP Theophylline RSin dilute hydrochloric acid (1in 100),and dilute quantitatively and stepwise with the same solvent to obtain a solution having a known concentration of about 8µg per mL.
Assay preparation— Pipet an accurately measured volume of Rectal Solution,equivalent to about 500mg of aminophylline,into a 500-mLvolumetric flask,dilute with water to volume,and mix.Pipet 5mLof this solution into a second 500-mLvolumetric flask,add 50mLof dilute hydrochloric acid (1in 10),dilute with water to volume,and mix.
Procedure— Concomitantly determine the absorbances of the Standard preparationand the Assay preparationin 1-cm cells at the wavelength of maximum absorbance at about 270nm,with a suitable spectrophotometer,using dilute hydrochloric acid (1in 100)as the blank.Calculate the quantity,in mg,of anhydrous theophylline (C7H8N4O2)in each mLof the Rectal Solution taken by the formula:
50(C/V)(AU/AS),
in which Cis the concentration,in µg per mL,of USP Theophylline RSin the Standard preparation;Vis the volume,in mL,of Rectal Solution taken;and AUand ASare the absorbances of the Assay preparationand the Standard preparation,respectively.
Auxiliary Information— Staff Liaison:Karen A Russo,Ph.D.,Scientist
Expert Committee:(PA1)Pharmaceutical Analysis 1
USP28–NF23Page 130
Pharmacopeial Forum:Volume No.27(1)Page 1748
Phone Number:1-301-816-8379
Return