Levetiracetam
(lee'' va tye ra' se tam).
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C8H14N2O2 170.21
1-Pyrrolidineacetamide, -ethyl-2-oxo-, (S)-;    
()-(S)--Ethyl-2-oxo-1-pyrrolidineacetamide     [102767-28-2].
DEFINITION
Levetiracetam contains NLT 98.0% and NMT 102.0% of C8H14N2O2, calculated on the anhydrous and solvent-free basis.
IDENTIFICATION
•  B. The retention time of the major peak for levetiracetam from the Sample solution corresponds to that of the levetiracetam S-enantiomer from the System suitability solution, as obtained in the test for Limit of Levetiracetam R-Enantiomer.
ASSAY
•  Procedure
Buffer:  2.7 g/L of monobasic potassium phosphate in water. Adjust with 2% aqueous potassium hydroxide (w/v) to a pH of 5.5.
Solution A:  Acetonitrile and Buffer (1:19)
Solution B:  Acetonitrile
Mobile phase:  See the gradient table below.
Time
(min)
Solution A
(%)
Solution B
(%)
0 100 0
3 100 0
20 71 29
System suitability solution:  0.2 mg/mL of USP Levetiracetam RS and 0.08 mg/mL of USP Levetiracetam Related Compound A RS in Solution A. Prepare by first dissolving the required amount of USP Levetiracetam RS in a suitable volumetric flask. Add 10% of the flask volume of 0.1 N potassium hydroxide. Let the mixture react at room temperature for about 15 min, and then neutralize by adding 0.1 N hydrochloric acid at 10% of the flask volume. Add the required amount of USP Levetiracetam Related Compound A RS, sonicate to dissolve, dilute with Solution A to volume, and mix.
Standard solution:  0.1 mg/mL of USP Levetiracetam RS in Solution A
Sample solution:  0.1 mg/mL of Levetiracetam in Solution A
Chromatographic system 
Mode:  LC
Detector:  UV 205 nm
Column:  4.6-mm × 15-cm; packing L1
Flow rate:  0.9 mL/min
Injection size:  10 µL
System suitability 
Sample:  System suitability solution
[Note—The relative retention times are given in Impurity Table 1. ]
Suitability requirements 
Relative standard deviation:  NMT 1.0%
[Note—If system suitability criteria cannot be met, it is recommended that the column temperature be maintained at 20 to stabilize the system. ]
Analysis 
Samples:  Standard solution and Sample solution
Calculate the percentage of C8H14N2O2 in the portion of Levetiracetam taken:
Result = [(rU/rS) × (CS/CU) × 100] F
rU== peak response of levetiracetam from the Sample solution
rS== peak response of levetiracetam from the Standard solution
CS== concentration of USP Levetiracetam RS in the Standard solution (mg/mL)
CU== concentration of Levetiracetam in the Sample solution (mg/mL)
F== percentage of levetiracetam R-enantiomer from the test for Limit of Levetiracetam R-Enantiomer
Acceptance criteria:  98.0%–102.0% on the anhydrous and solvent-free basis
IMPURITIES
Inorganic Impurities 
•  Residue on Ignition 281: NMT 0.1%
Organic Impurities 
•  Procedure 1: Limit of Levetiracetam Related Compound B
[Note—Perform this test only if levetiracetam related compound B is a known process impurity. ]
Buffer:  1.22 g of sodium 1-decanesulfonate in 1 L of water containing about 1.3 mL of phosphoric acid. Adjust with 20% (w/v) potassium hydroxide to a pH of 3.0.
Mobile phase:  Acetonitrile and Buffer (3:17)
System suitability solution:  2 mg/mL of USP Levetiracetam Related Compound B RS in Mobile phase
Standard solution:  0.002 mg/mL of USP Levetiracetam Related Compound B RS in Mobile phase
Sample solution:  2.0 mg/mL of Levetiracetam in Mobile phase
Chromatographic system 
Mode:  LC
Detector:  UV 200 nm
Column:  4.6-mm × 25-cm; packing L1
Flow rate:  1.0 mL/min
Injection size 
System suitability:  10 µL
Analysis:  50 µL
System suitability 
Sample:  System suitability solution
[Note—The retention time for levetiracetam related compound B is 9 min. ]
Suitability requirements 
Tailing factor:  NMT 3.0
[Note—If a significant tailing of the levetiracetam related compound B peak is observed (greater than 3.0), it is recommended that the column temperature be maintained at 27 to stabilize the system. ]
Relative standard deviation:  NMT 2.0%
Analysis 
Samples:  Standard solution and Sample solution
Calculate the percentage of levetiracetam related compound B in the portion of Levetiracetam taken:
Result = (rU/rS) × (CS/CU) × (Mr1/Mr2) × 100
rU== peak response of levetiracetam related compound B from the Sample solution
rS== peak response of levetiracetam related compound B from the Standard solution
CS== concentration of USP Levetiracetam Related Compound B RS in the Standard solution (mg/mL)
CU== concentration of Levetiracetam in the Sample solution (mg/mL)
Mr1== molecular weight of levetiracetam related compound B free base, 102.1
Mr2== molecular weight of levetiracetam related compound B, 138.6
Acceptance criteria:  NMT 0.10%
[Note—The amount of levetiracetam related compound B measured is to be included in the total impurities in the test for Organic Impurities, Procedure 2. ]
•  Procedure 2
Buffer, Solution A, Solution B, Mobile phase, System suitability solution, and Chromatographic system:  Proceed as directed in the Assay.
Standard solution:  0.005 mg/mL of USP Levetiracetam RS in Solution A
Sample solution:  5 mg/mL of Levetiracetam in Solution A
Analysis 
Samples:  Standard solution and Sample solution
Calculate the percentage of each impurity in the portion of Levetiracetam taken:
Result = (rU/rS) × (CS/CU) × (1/F) × 100
rU== peak response of each impurity from the Sample solution
rS== peak response of levetiracetam from the Standard solution
CS== concentration of USP Levetiracetam RS in the Standard solution (mg/mL)
CU== concentration of Levetiracetam in the Sample solution (mg/mL)
F== relative response factor (see Impurity Table 1)
[Note—Disregard any peak with a relative retention time of 0.19 or less. ]
Acceptance criteria 
Individual impurities:  See Impurity Table 1.
Total impurities:  NMT 0.4%
Impurity Table 1
Name Relative
Retention
Time
Relative
Response
Factor
Acceptance
Criteria,
NMT (%)
Pyridin-2-ola 0.37 1.0 0.025
Levetiracetam acidb 0.62 1.2 0.3
Levetiracetam 1.00
Levetiracetam related compound Ac 1.25 0.35 0.05
Any individual unspecified impurity 1.0 0.05
a  Not included in the Total impurities limit.
b  (S)-2-(2-Oxopyrrolidin-1-yl)butanoic acid. Included in the Total impurities limit.
c  (S)-N-(1-Amino-1-oxobutan-2-yl)-4-chlorobutanamide. Included in the Total impurities limit only if levetiracetam related compound B is a known process impurity.
SPECIFIC TESTS
•  Limit of Levetiracetam R-Enantiomer
Mobile phase:  n-Hexane and dehydrated alcohol (4:1)
System suitability solution:  0.1 mg/mL of USP Levetiracetam Racemic Mixture RS in Mobile phase
Standard solution:  0.05 mg/mL of USP Levetiracetam RS in Mobile phase
Sample solution:  10 mg/mL of Levetiracetam in Mobile phase
Chromatographic system 
Mode:  LC
Detector:  UV 215 nm
Column:  4.6-mm × 25-cm; 10-µm packing L51
Flow rate:  1.0 mL/min
Injection size:  20 µL
System suitability 
Sample:  System suitability solution
[Note—The relative retention times for levetiracetam R-enantiomer and levetiracetam S-enantiomer are 0.55 and 1.0, respectively. ]
Suitability requirements 
Resolution:  NLT 4.0 between the R- and S-enantiomers
[Note—If a loss of resolution (less than 4.0) is observed, it is recommended that the column temperature be maintained at 25 to stabilize the system. ]
Analysis 
Samples:  Standard solution and Sample solution
Calculate the percentage of levetiracetam R-enantiomer in the portion of Levetiracetam taken:
Result = (rU/rS) × (CS/CU) × 100
rU== peak response of levetiracetam R-enantiomer from the Sample solution
rS== peak response of levetiracetam from the Standard solution
CS== concentration of USP Levetiracetam RS in the Standard solution (mg/mL)
CU== concentration of Levetiracetam in the Sample solution (mg/mL)
Acceptance criteria:  NMT 0.8%
ADDITIONAL REQUIREMENTS
•  Packaging and Storage: Preserve in well-closed containers, and store at room temperature.
•  USP Reference Standards 11
USP Levetiracetam RS Click to View Structure
USP Levetiracetam Racemic Mixture RS
A 1:1 mixture of levetiracetam S-enatiomer-(2S)-2-(2-oxopyrrolidin-1-yl)butanamide and levetiracetam R-enantiomer (2R)-2-(2-oxopyrrolidin-1-yl)butanamide.
USP Levetiracetam Related Compound A RS
(S)-N-(1-Amino-1-oxobutan-2-yl)-4-chlorobutanamide.
    C8H14ClNO3         207.65
USP Levetiracetam Related Compound B RS
(S)-2-Aminobutanamide hydrochloride.
    C4H10N2O·HCl        138.6
Auxiliary Information— Please check for your question in the FAQs before contacting USP.
Topic/Question Contact Expert Committee
Monograph Hariram Ramanathan, M.S.
Associate Scientific Liaison
1-301-816-8313
(SM42010) Monographs - Small Molecules 4
Reference Standards RS Technical Services
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rstech@usp.org
USP35–NF30 Page 3659
Pharmacopeial Forum: Volume No. 36(5) Page 1147