Levetiracetam

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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C₈H₁₄N₂O₂ 170.21

1-Pyrrolidineacetamide, α-ethyl-2-oxo-, (αS)-;

(−)-(S)-α-Ethyl-2-oxo-1-pyrrolidineacetamide CAS RN®: 102767-28-2; UNII: 44YRR34555.

1 DEFINITION

Levetiracetam contains NLT 98.0% and NMT 102.0% of levetiracetam (C₈H₁₄N₂O₂ ), calculated on the anhydrous and solvent-free basis.

2 IDENTIFICATION

Change to read:

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197K (CN 1-May-2020)

B. The retention time of the major peak of the Identification 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.

3 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 Table 1.

Table 1

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. [Note—Levetiracetam related compound A is included for peak identification purposes.]

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

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 205 nm

Column: 4.6-mm × 15-cm; packing L1

Flow rate: 0.9 mL/min

Injection volume: 10 μL

System suitability

Sample: System suitability solution

[Note—See Table 2 for relative retention times.]

Suitability requirements

Relative standard deviation: NMT 1.0%, for the levetiracetam peak

[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 levetiracetam (C₈H₁₄N₂O₂ ) in the portion of Levetiracetam taken:

Result = [(r_U/r_S)x(C_S/C_U ) × 100] − F

r_U = peak response of levetiracetam from the Sample solution

r_S = peak response of levetiracetam from the Standard solution

C_S = concentration of USP Levetiracetam RS in the Standard solution (mg/mL)

C_U = 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

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.1%

Limit of Levetiracetam R-Enantiomer

Mobile phase: n-Hexane and dehydrated alcohol (80:20)

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

Identification solution: 0.05 mg/mL of Levetiracetam from Sample solution in Mobile phase

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 215 nm

Column: 4.6-mm × 25-cm; 10-μm packing L51

Flow rate: 1.0 mL/min

Injection volume: 20 μL

System suitability

Samples: System suitability solution and Identi

cation solution

[Note—The relative retention times for levetiracetam R-enantiomer and levetiracetam S-enantiomer are 0.55 and 1.0, respectively. Use the chromatogram from the Identification solution for Identi

cation test B.]

Suitability requirements

Resolution: NLT 4.0 between the R- and S-enantiomers, System suitability solution. [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 = (r_U /r_S ) × (C_S /C_U ) × 100

r_U = peak response of levetiracetam R-enantiomer from the Sample solution

r_S = peak response of levetiracetam from the Standard solution

C_S = concentration of USP Levetiracetam RS in the Standard solution (mg/mL)

C_U = concentration of Levetiracetam in the Sample solution (mg/mL)

Acceptance criteria: NMT 0.8%

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

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 200 nm

Column: 4.6-mm × 25-cm; packing L1

Flow rate: 1.0 mL/min

Injection volumes

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 signi

cant 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 = (r_U/r_S)x(C_S/C_U) × (M_r1 /M_r2 ) × 100

r_U = peak response of levetiracetam related compound B from the Sample solution

r_S = peak response of levetiracetam related compound B from the Standard solution

C_S = concentration of USP Levetiracetam Related Compound B RS in the Standard solution (mg/mL)

C_U = concentration of Levetiracetam in the Sample solution (mg/mL)

M_r1 = molecular weight of levetiracetam related compound B free base, 102.1

M_r2 = 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.]

Organic Impurities

Buffer, Solution A, Solution B, Mobile phase, System suitability solution, Chromatographic system, and System suitability: 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 = (r_U/r_S)x(C_S/C_U) × (1/F) × 100

r_U = peak response of each impurity from the Sample solution

r_S = peak response of levetiracetam from the Standard solution

C_S = concentration of USP Levetiracetam RS in the Standard solution (mg/mL)

C_U = concentration of Levetiracetam in the Sample solution (mg/mL)

F = relative response factor (see Table 2)

[Note—Disregard any peak with a relative retention time of 0.19 or less.]

Acceptance criteria: See Table 2.

Table 2

^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.

5 SPECIFIC TESTS

Water Determination 〈921〉, Method Ia: NMT 0.5%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers, and store at room temperature.

USP Reference Standards 〈11〉

USP Levetiracetam RS

USP Levetiracetam Racemic Mixture RS

A 1:1 mixture of:

Levetiracetam S-enantiomer-(2S)-2-(2-oxopyrrolidin-1-yl)butanamide;

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.

C₈H₁₅ClN₂O₂ 206.67

USP Levetiracetam Related Compound B RS

(S)-2-Aminobutanamide hydrochloride.

C₈H₁₄N₂O₂ · HCl 138.6