Aminophylline Oral Solution
» Aminophylline Oral Solution is an aqueous solution of Aminophylline, prepared with the aid of Ethylenediamine. It contains an amount of aminophylline equivalent to not less than 90.0 percent and not more than 110.0 percent of the labeled amount of anhydrous theophylline (C7H8N4O2).
Aminophylline Oral Solution may contain an excess of ethylenediamine, but no other substance may be added for the purpose of pH adjustment.
Packaging and storage— Preserve in tight containers.
Labeling— Label the Oral Solution to state the content of anhydrous theophylline.
USP Reference standards 11
USP Theophylline RS Click to View Structure
A: Place a volume of Oral Solution, equivalent to about 500 mg of aminophylline, in a suitable container, and add, with constant stirring, 1 mL of 3 N hydrochloric acid or an amount sufficient to precipitate the theophylline completely. Filter (retain the filtrate), wash the precipitate with small portions of cold water until free from chloride, and dry at 105 for 1 hour: the theophylline so obtained melts between 270 and 274.
B: The filtrate from Identification test A responds to Identification test C under Aminophylline.
pH 791: between 8.5 and 9.7.
Ethylenediamine content— Accurately measure a volume of Oral Solution, equivalent to about 500 mg of aminophylline, and dilute with water, if necessary, to make about 30 mL. Add methyl orange TS, and titrate with 0.1 N hydrochloric acid VS. Each mL of 0.1 N hydrochloric acid is equivalent to 3.005 mg of C2H8N2. The Oral Solution contains between 176 mg and 283 mg of ethylenediamine (C2H8N2) per g of C7H8N4O2 found in the Assay.
Mobile phase, Diluent, Standard preparation, Resolution solution, and Chromatographic system Prepare as directed in the Assay under Aminophylline.
Assay preparation— Transfer an accurately measured volume of Oral Solution, equivalent to about 18 mg of anhydrous theophylline, to a 250-mL volumetric flask, dilute with Diluent to volume, and mix.
Procedure— Proceed as directed for Procedure in the Assay under Aminophylline. Calculate the quantity, in mg, of theophylline (C7H8N4O2) in each mL of the Oral Solution taken by the formula:
250(C / V)(rU / rS)
in which C is the concentration, in mg per mL, of USP Theophylline RS in the Standard preparation; V is the volume, in mL, of Oral Solution taken; and rU and rS are the theophylline peak responses obtained from the Assay preparation and the Standard preparation, respectively.
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Monograph Domenick Vicchio, Ph.D.
Senior Scientific Liaison
(SM42010) Monographs - Small Molecules 4
Reference Standards RS Technical Services
USP35–NF30 Page 2174