Articaine Hydrochloride
(ar' ti kane hye'' droe klor' ide).
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C13H20N2O3S·HCl 320.84
2-Thiophenecarboxylic acid, 4-methyl-3-[[1-oxo-2-(propylamino)propyl]amino]-, methyl ester, monohydrochloride;    
Methyl 4-methyl-3-[2-(propylamino)propionamido]-2-thiophenecarboxylate, monohydrochloride     [23964-57-0].
DEFINITION
Articaine Hydrochloride contains NLT 98.5% and NMT 101.0% of C13H20N2O3S·HCl, calculated on the dried basis.
IDENTIFICATION
•  A. Infrared Absorption 197
Standard solution:  12 mg/mL of USP Articaine RS in methylene chloride. Transfer 20 µL of this solution onto a 300-mg disk.
Sample solution:  Dissolve 100 mg of Articaine Hydrochloride in 5 mL of water. Add 3 mL of a saturated solution of sodium bicarbonate, and shake twice with 2 mL of methylene chloride. Combine the methylene chloride layers, dilute with methylene chloride to 5.0 mL, and dry over anhydrous sodium sulphate. Transfer 20 µL of this solution onto a 300-mg disk.
ASSAY
•  Procedure
Sample solution:  250 mg of Articaine Hydrochloride to a 250-mL conical flask. Add 5.0 mL of 0.01 M hydrochloric acid and 50 mL of alcohol. Stir to dissolve.
Analysis:  Titrate with 0.1 M sodium hydroxide VS, determining the endpoint potentiometrically, using a glass electrode. Calculate the volume of sodium hydroxide consumed by reading the volume added between the two points of inflection. Each mL of 0.1 M sodium hydroxide is equivalent to 32.08 mg of C13H20N2O3S·HCl.
Acceptance criteria:  98.5%–101.0% on the dried basis.
IMPURITIES
Inorganic Impurities 
•  Heavy Metals, Method I 231
Sample solution:  200 mg/mL of Articaine Hydrochloride
Acceptance criteria:  NMT 5 ppm
•  Residue on Ignition 281
Sample:  1 g
Acceptance criteria:  NMT 0.1%
Organic Impurities 
•  Procedure
Buffer solution:  2.02 g of sodium 1-heptanesulfonate and 4.08 g of potassium dihydrogen phosphate in 1 L of water. Adjust with phosphoric acid to a pH of 2.0.
Mobile phase:  Acetonitrile and Buffer solution (1:3)
Standard solution:  2 µg/mL of USP Articaine Related Compound A , and 1 µg/mL each of USP Articaine Related Compound E RS and USP Articaine Hydrochloride RS in Mobile phase. [Note—This solution is also used to determine the reporting threshold limit. ]
Sample solution:  1.0 mg/mL of Articaine Hydrochloride in Mobile phase
Chromatographic system  
Mode:  LC
Detector:  UV 276 nm
Column:  4.6-mm × 25-cm; packing L1
Temperature:  45
Flow rate:  1 mL/min
Injection size:  10 µL
System suitability 
Sample:  Standard solution
Suitability requirements 
Resolution:  NLT 1.2 between articaine related compound A and articaine related compound E
Analysis 
Samples:  Standard solution and Sample solution. [Note—Run time is 5 times the retention time of articaine. ]
Calculate the percentage of any articaine related compound A in the portion of Articaine Hydrochloride taken:
Result = (rU/rS) × (CS/CU) × 100
rU== response of articaine related compound A from the Sample solution
rS== response of articaine related compound A from the Standard solution
CS== concentration of USP Articaine Related Compound A RS in the Standard solution (mg/mL)
CU== concentration of Articaine Hydrochloride in the Sample solution (mg/mL)
Calculate the percentage of each individual impurity in the portion of Articaine Hydrochloride taken:
Result = (rU/rS) × (CS/CU) × 100
rU== response of each individual impurity from the Sample solution
rS== response of articaine hydrochloride from the Standard solution
CS== concentration of USP Articaine Hydrochloride RS in the Standard solution (mg/mL)
CU== concentration of Articaine Hydrochloride in the Sample solution (mg/mL)
[Note—Disregard any peak below 0.05%. ]
Acceptance criteria 
Individual impurities:  See Impurity Table 1.
Total impurities:  NMT 0.5%. [Note—Excluding articaine related compound A. ]
Impurity Table 1
Name Relative
Retention
Time
Acceptance
Criteria,
NMT (%)
Articaine acida 0.6 0.1
Ethylarticaineb 0.7 0.1
Articaine related compound Ac 0.8 0.2
Articaine related compound Ed 0.86 0.1
Articaine acid-propionamidee 0.9 0.1
Articaine 1.0
Butylarticainef 1.7 0.1
Dipropylarticaineg 2.1 0.1
3-Aminoarticaineh 2.6 0.1
Articaine isopropyl esteri 3.6 0.1
Bromo compoundj 4.0 0.1
Any other individual impurity 0.10
a  4-Methyl-3-[[(2RS)-2-(propylamino)propanoyl]amino]thiophene-2-carboxylic acid.
b  Methyl 3-[[(2RS)-2-(ethylamino)propanoyl]amino]-4-methylthiophene-2-carboxylate.
c  Methyl 4-methyl-3-[2-(propylamino)acetamido]thiophene-2-carboxylate.
d  Methyl 3-[2-(isopropylamino)propanamido]-4-methylthiophene-2-carboxylate.
e  4-Methyl-N-propyl-3-[[(2RS)-2-(propylamino)propanoyl]amino]thiophene-2-carboxamide.
f  Methyl 3-[[(2RS)-2-(butylamino)propanoyl]amino]-4-methylthiophene-2-carboxylate.
g  Methyl 3-[[(2RS)-2-(dipropylamino)propanoyl]amino]-4-methylthiophene-2-carboxylate.
h  Methyl 3-amino-4-methylthiophene-2-carboxylate.
i  1-Methylethyl 4-methyl-3-[[(2RS)-2-(propylamino)propanoyl]amino]
thiophene-2-carboxylate.
j  Methyl 3-[[(2RS)-2-bromopropanoyl]amino]-4-methylthiophene-2-carboxylate.
SPECIFIC TESTS
•   Loss on Drying 731: Dry at 105 for 5 h: it loses NMT 0.5% of its weight.
•   pH 791
Sample solution:  10 mg/mL
Acceptance criteria:  4.2–5.2
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in light-resistant containers.
•  USP Reference Standards 11
USP Articaine RS Click to View Structure
USP Articaine Hydrochloride RS
USP Articaine Related Compound A RS Click to View Structure
Methyl 4-methyl-3-[2-(propylamino) acetamido]thiophene-2-carboxylate.
    C12H18N2O3S         270.35
USP Articaine Related Compound E RS Click to View Structure
Methyl 3-[2-(isopropylamino) propanamido]-4-methylthiophene-2-carboxylate.
    C13H20N2O3S        284.37
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Domenick Vicchio, Ph.D.
Senior Scientific Liaison
1-301-998-6828
(SM42010) Monographs - Small Molecules 4
Reference Standards RS Technical Services
1-301-816-8129
rstech@usp.org
USP35–NF30 Page 2241
Pharmacopeial Forum: Volume No. 35(3) Page 544