Dextromethorphan
;)
Morphinan,3-methoxy-17-methyl-,(9a,13a,14a)-.
3-Methoxy-17-methyl-9a,13a,14a-morphinan [125-71-3].
»Dextromethorphan contains not less than 98.0percent and not more than 101.0percent of C18H25NO,calculated on the anhydrous basis.
Packaging and storage—
Preserve in tight containers.
Identification—
A:
Infrared Absorption á197Kñ.
Solution:
100µg per mL.
Medium:
dilute hydrochloric acid (1in 120).
Absorptivities at 278nm,calculated on the anhydrous basis,do not differ by more than 3.0%.
and 112.5
Specific rotation á781Sñ—
Test solution:
100mg per mL,in chloroform.Its specific rotation does not differ from that of the similarly prepared solution of USP Dextromethorphan RSby more than 1.0%.
Water,Method Ia á921ñ:
not more than 0.5%.
Residue on ignition á281ñ:
not more than 0.1%.
Heavy metals,Method IIá231ñ:
0.002%.
Limit of N,N-dimethylaniline—
Standard solution—
Transfer about 50mg of N,N-dimethylaniline to a 100-mLvolumetric flask,add 70.0mLof water,insert the stopper tightly,shake for 20minutes using a mechanical wrist-action shaker or equivalent,dilute with water to volume,and mix.Transfer 1.0mLto a 100-mLvolumetric flask,dilute with water to volume,transfer 1.0mLof this solution to a 25-mLvolumetric flask,and add 19mLof water.
Test solution—
Transfer about 500mg of Dextromethorphan,accurately weighed,to a 25-mLvolumetric flask,add 19mLof water and 1mLof 3Nhydrochloric acid,dissolve by warming on a steam bath,and cool.
Procedure—
Add 2mLof 1Nacetic acid and 1mLof sodium nitrite solution (1in 100)to the Test solution,dilute with water to volume,and mix.This solution shows no more color than the straw yellow to greenish yellow color of the solution obtained from the Standard solutionsimilarly treated:not more than 0.001%of N,N-dimethylaniline is found.
Limit of phenolic compounds—
Dissolve about 10mg in 2mLof 3Nhydrochloric acid,and add 2drops of ferric chloride TS.Mix,add 2drops of potassium ferricyanide TS,and observe after 2minutes:no blue-green color develops.
Assay—
Dissolve about 700mg of Dextromethorphan,accurately weighed,in 60mLof glacial acetic acid,warming slightly,if necessary,to dissolve.Add 2drops of crystal violet TS,and titrate with 0.1Nperchloric acid VSto a blue-green endpoint.Perform a blank determination,and make any necessary correction.Each mLof 0.1Nperchloric acid is equivalent to 27.14mg of C18H25NO.
Auxiliary Information—
Staff Liaison:Clydewyn M.Anthony,Ph.D.,Scientist
Expert Committee:(PA2)Pharmaceutical Analysis 2
USP28–NF23Page 610
Phone Number:1-301-816-8139