Identification—
Disperse a portion of powdered Tablets, equivalent to about 25 mg of chlorpheniramine maleate, in about 20 mL of dilute hydrochloric acid (1 in 100). Dissolve about 25 mg of
USP Chlorpheniramine Maleate RS in 20 mL of dilute hydrochloric acid (1 in 100). Treat each solution as follows. Render alkaline, to a pH of about 11, with sodium hydroxide solution (1 in 10). Extract with two 50-mL portions of solvent hexane, collect the extracts in a beaker, and evaporate to dryness. Prepare a mineral oil dispersion of the residue so obtained and determine the IR absorption spectrum of the preparation in the region between 2 µm and 12 µm: the spectrum of the test preparation exhibits maxima only at the same wavelengths as that of the Standard preparation.
Dissolution 
711
—
Medium:
0.01 N hydrochloric acid; 500 mL
Apparatus 2:
50 rpm.
Time:
30 minutes.
Procedure—
Determine the amount of C16H19ClN2·C4H4O4 dissolved by employing UV absorption at the wavelength of maximum absorbance at about 265 nm on 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 Chlorpheniramine Maleate RS in the same Medium.
Tolerances—
Not less than 80% (Q) of the labeled amount of C16H19ClN2·C4H4O4 is dissolved in 30 minutes.
Assay—
Using a portion of powdered Tablets equivalent to 4 mg of chlorpheniramine maleate, proceed as directed under
Salts of Organic Nitrogenous Bases 501, but using dilute hydrochloric acid (1 in 100) instead of the dilute sulfuric acid (1 in 350), and dilute sulfuric acid (1 in 70), and using solvent hexane instead of the ether, and diluting 10 mL of the
Assay preparation with dilute hydrochloric acid (1 in 100) to 25.0 mL to prepare the solution employed for the determination of the absorbance,
AU, at 264 nm. For the determination of
AS, prepare a solution containing about 40 mg of
USP Chlorpheniramine Maleate RS, accurately weighed, in 200.0 mL of dilute hydrochloric acid (1 in 100), and treat 20.0 mL of this solution the same as the solution in dilute hydrochloric acid (1 in 100) of the portion of Tablets taken. Calculate the quantity, in mg, of C
16H
19ClN
2·C
4H
4O
4 in the portion of Tablets taken by the formula:
C(AU / AS),
in which
C is the weight, in mg, of
USP Chlorpheniramine Maleate RS in the 20.0-mL portion of the
Standard preparation.
