(dex'' klor fen ir' a meen mal' ee ate).
2-Pyridinepropanamine, -(4-chlorophenyl)-N,N-dimethyl-, (S)-, (Z)-2-butenedioate (1:1).
(+)-2-[p-Chloro--[2-(dimethylamino)ethyl]benzyl]pyridine maleate (1:1) [2438-32-6].
» Dexchlorpheniramine Maleate, dried at 65 for 4 hours, contains not less than 98.0 percent and not more than 100.5 percent of C16H19ClN2·C4H4O4.
Packaging and storage Preserve in tight, light-resistant containers.
USP Reference standards 11
Solution: 40 µg per mL.
Melting range, Class I 741: between 110 and 115.
Specific rotation 781S: between +39.5 and +43.0.
Test solution: 50 mg per mL, in dimethylformamide.
pH 791: between 4.0 and 5.0, in a solution (1 in 100).
Loss on drying 731 Dry it at 65 for 4 hours: it loses not more than 0.5% of its weight.
Residue on ignition 281: not more than 0.2%.
Test solution Dissolve about 200 mg of Dexchlorpheniramine Maleate in 5 mL of methylene chloride, and mix.
Chromatographic system (see Chromatography 621)The gas chromatograph is equipped with a flame-ionization detector and a 1.2-m × 4-mm glass column containing 3% phase G3 on support S1AB. The column temperature is maintained at about 190, and the injection port and detector temperatures are both maintained at about 250. The carrier gas is dry helium, flowing at a rate adjusted to obtain a retention time of 4 to 5 minutes for the main peak. Chromatograph the Test solution, record the chromatogram, and determine the peak area as directed under Procedure: the tailing factor for the dexchlorpheniramine maleate peak is not more than 1.8.
Procedure Inject a volume (about 1 µL) of the Test solution into the chromatograph. Record the chromatogram for a total time of not less than twice the retention time of the dexchlorpheniramine peak, and measure the areas of the peaks. The total relative area of all extraneous peaks (except that of the solvent peak and maleic acid, if observed) does not exceed 2.0%.
Assay Dissolve about 400 mg of Dexchlorpheniramine Maleate, previously dried and accurately weighed, in 50 mL of glacial acetic acid, add 1 drop of crystal violet TS, and titrate with 0.1 N perchloric acid VS to a green endpoint. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N perchloric acid is equivalent to 19.54 mg of C16H19ClN2·C4H4O4.
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USP35NF30 Page 2848