Packaging and storage—
Preserve in single-dose containers from which carbon dioxide has been excluded, preferably of Type I glass, protected from light.
Labeling—
Label the Injection to state the content of anhydrous theophylline.
Identification—
A:
Dilute a volume of Injection, equivalent to about 500 mg of aminophylline, with water to about 20 mL, and add, with constant stirring, 1 mL of 3 N hydrochloric acid or enough to precipitate the theophylline completely. Filter: the filtrate responds to
Identification test
C under
Aminophylline.
B:
Wash the precipitate of theophylline with a small portion of cold water, and dry at 105
for 1 hour: the theophylline so obtained melts between 270
and 274
, and responds to
Identification test
B under
Aminophylline.
Ethylenediamine content—
Accurately measure a volume of Injection, 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 C
2H
8N
2. The Injection contains between 166 mg and 192 mg of ethylenediamine (C
2H
8N
2) per g of C
7H
8N
4O
2 found in the
Assay.
Other requirements—
It meets the requirements under
Injections 
1
.
Assay—
Mobile phase, Diluent, Standard preparation, Resolution solution, and Chromatographic system—
Proceed as directed in the
Assay under
Aminophylline.
Assay preparation—
Transfer an accurately measured volume of Injection, equivalent to about 100 mg of theophylline, to a 100-mL volumetric flask, dilute with Diluent to volume, and mix. Pipet 4 mL of this solution into a 50-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 (C
7H
8N
4O
2) in the portion of Injection taken by the formula:
1250C(rU / rS),
in which
C is the concentration, in mg per mL, of
USP Theophylline RS in the
Standard preparation; and
rU and
rS are the theophylline peak responses obtained from the
Assay preparation and the
Standard preparation, respectively.
