Lidocaine
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C14H22N2O 234.34

Acetamide,2-(diethylamino)-N-(2,6-dimethylphenyl)-.
2-(Diethylamino)-2¢,6¢-acetoxylidide [137-58-6].
»Lidocaine contains not less than 97.5percent and not more than 102.5percent of C14H22N2O.
Packaging and storage— Preserve in well-closed containers.
Identification—
A: Infrared Absorption á197Kñ:previously dried in vacuum over silica gel for 24hours.
B: To about 100mg dissolved in 1mLof alcohol add 10drops of cobaltous chloride TS,and shake the solution for about 2minutes:a bright green color develops,and a fine precipitate is formed.
Melting range á741ñ: between 66and 69.
Residue on ignition á281ñ: not more than 0.1%.
Chloride á221ñ— Dissolve 1.0g in a mixture of 3mLof 2Nnitric acid and 12mLof water,and add 1mLof silver nitrate TS:the turbidity does not exceed that produced by 50µLof 0.020Nhydrochloric acid (0.0035%).
Sulfate— Dissolve about 200mg in a mixture of 2mLof 2Nnitric acid and 20mLof water,and filter if necessary.To one-half of the filtrate add 1mLof barium chloride TS:no more turbidity is produced than is present in the remaining portion of the filtrate to which nothing has been added.
Heavy metals,Method Iá231ñ— Dissolve 1.0g in a mixture of 2mLof 3Nhydrochloric acid and 10mLof water,evaporate on a steam bath to dryness,and dissolve the residue in 25mLof water:the limit is 0.002%.
Assay—
Mobile phase,Standard preparation,Resolution preparation,and Chromatographic system— Prepare as directed in the Assayunder Lidocaine Hydrochloride.
Assay preparation— Dissolve about 85mg of Lidocaine,accurately weighed,with warming if necessary,in 0.5mLof 1Nhydrochloric acid in a 50-mLvolumetric flask,dilute with Mobile phaseto volume,and mix.
Procedure— Proceed as directed for Procedurein the Assayunder Lidocaine Hydrochloride.Calculate the quantity,in mg,of C14H22N2Oin the portion of Lidocaine taken by the formula:
50C(rU/rS),
in which Cis the concentration,in mg per mL,of USP Lidocaine RSin the Standard preparation,and rUand rSare the lidocaine peak responses obtained from the Assay preparationand the Standard preparation,respectively.
Auxiliary Information— Staff Liaison:Karen A Russo,Ph.D.,Scientist
Expert Committee:(PA1)Pharmaceutical Analysis 1
USP28–NF23Page 1129
Phone Number:1-301-816-8379