Lidocaine Hydrochloride
(lye' doe kane hye'' droe klor' ide).

C14H22N2O·HCl·H2O 288.81
Acetamide, 2-(diethylamino)-N-(2,6-dimethylphenyl)-, monohydrochloride, monohydrate;    
2-(Diethylamino)-2',6'-acetoxylidide monohydrochloride monohydrate     [6108-05-0].
Anhydrous     270.80 [73-78-9].
DEFINITION
Lidocaine Hydrochloride contains NLT 97.5% and NMT 102.5% of C14H22N2O·HCl, calculated on the anhydrous basis.
IDENTIFICATION
•  A. Infrared Absorption 197K
Standard:  Prepare as directed in 197K, using USP Lidocaine RS.
Sample:  Dissolve 300 mg in 5–10 mL of water in a separator, add 4 mL of 6 N ammonium hydroxide, and extract with four 15-mL portions of chloroform. Combine the chloroform extracts, evaporate with the aid of a current of warm air, and dry the residue in vacuum over silica gel for 24 h.
Acceptance criteria:  Meets the requirements
•  B. The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.
•  C. Identification Tests—General, Chloride 191: Meets the requirements
ASSAY
•  Procedure
Solution A:  Water and glacial acetic acid (930:50). Adjust with 1 N sodium hydroxide to a pH of 3.40.
Mobile phase:  Acetonitrile and Solution A (1:4), so that the retention time of lidocaine is 4–6 min
Standard solution:  Dissolve 85 mg of USP Lidocaine RS, with warming if necessary, in 0.5 mL of 1 N hydrochloric acid in a 50-mL volumetric flask. Dilute with Mobile phase to volume (1.7 mg/mL of lidocaine).
System suitability stock solution:  220 µg/mL of methylparaben in Mobile phase
System suitability solution:  Mix 2 mL of System suitability stock solution and 20 mL of Standard solution.
Sample solution:  2 mg/mL of Lidocaine Hydrochloride in Mobile phase
Chromatographic system 
Mode:  LC
Detector:  UV 254 nm
Column:  3.9-mm × 30-cm; packing L1
Flow rate:  1.5 mL/min
Injection size:  20 µL
System suitability 
Samples:  Standard solution and System suitability solution
Suitability requirements 
Resolution:  NLT 3.0 between lidocaine and methylparaben, System suitability solution
Relative standard deviation:  NMT 1.5%, Standard solution
Analysis 
Samples:  Standard solution and Sample solution
Calculate the percentage of C14H22N2O·HCl in the portion of Lidocaine Hydrochloride taken:
Result = (rU/rS) × (CS/CU) × (Mr1/Mr2) × 100
rU== peak response from the Sample solution
rS== peak response from the Standard solution
CS== concentration of USP Lidocaine RS in the Standard solution (mg/mL)
CU== concentration of Lidocaine Hydrochloride in the Sample solution (mg/mL)
Mr1== molecular weight of lidocaine hydrochloride, 270.80
Mr2== molecular weight of lidocaine, 234.34
Acceptance criteria:  97.5%–102.5% on the anhydrous basis
IMPURITIES
Inorganic Impurities 
•  Residue on Ignition 281: NMT 0.1%
•  Chloride and Sulfate, Sulfate 221: Dissolve 100 mg in 10 mL of water, and add 1 mL of 3 N hydrochloric acid. Mix, and add 1 mL of barium chloride TS. The turbidity does not exceed that produced by 0.10 mL of 0.020 N sulfuric acid (NMT 0.1%).
SPECIFIC TESTS
•  Melting Range or Temperature 741: 74–79
[Note—The preliminary drying treatment is omitted. ]
•  Water Determination, Method I 921: 5.0%–7.0%
•  Sterility Tests 71: Where the label states that Lidocaine Hydrochloride is sterile, it meets the requirements.
•  Bacterial Endotoxins Test 85: Where the label states that Lidocaine Hydrochloride is sterile or must be subjected to further processing during the preparation of injectable dosage forms, it contains NMT 1.1 USP Endotoxin Units/mg of lidocaine hydrochloride.
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in well-closed containers. Store at room temperature.
•  Labeling: Where it is intended for use in preparing injectable dosage forms, the label states that it is sterile or must be subjected to further processing during the preparation of injectable dosage forms.
•  USP Reference Standards 11
USP Endotoxin RS
USP Lidocaine RS Click to View Structure
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Mary S. Waddell
Scientific Liaison
1-301-816-8124
(SM42010) Monographs - Small Molecules 4
71 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
1-301-816-8339
(GCM2010) General Chapters - Microbiology
85 Radhakrishna S Tirumalai, Ph.D.
Principal Scientific Liaison
1-301-816-8339
(GCM2010) General Chapters - Microbiology
Reference Standards RS Technical Services
1-301-816-8129
rstech@usp.org
USP35–NF30 Page 3683
Pharmacopeial Forum: Volume No. 36(5) Page 1191