Methsuximide

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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C₁₂H₁₃NO₂  203.24

2,5-Pyrrolidinedione, 1,3-dimethyl-3-phenyl-, (±)-;

(±)-N,2-Dimethyl-2-phenylsuccinimide CAS RN^®: 77-41-8; UNII: 0G76K8X6C0.

1 DEFINITION

Methsuximide contains NLT 97.0% and NMT 103.0% of methsuximide (C₁₂H₁₃NO₂), calculated on the dried basis.

2 IDENTIFICATION

A. SPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 197K

B. The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

3.1 PROCEDURE

Mobile phase: Acetonitrile and water (9:11)

Standard solution: 0.6 mg/mL of USP Methsuximide RS in Mobile phase

Sample solution: 0.6 mg/mL of Methsuximide in Mobile phase

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 254 nm

Column: 3.9-mm × 30-cm; 10-µm packing L1

Flow rate: 1 mL/min

Injection volume: 20 µL

System suitability

Sample: Standard solution

Suitability requirements

Column efficiency: NLT 5800 theoretical plates

Tailing factor: NMT 1.3

Relative standard deviation: NMT 0.6%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of methsuximide (C₁₂H₁₃NO₂) in the portion of Methsuximide taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

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

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

Acceptance criteria: 97.0%-103.0% on the dried basis

4 IMPURITIES

4.1 RESIDUE ON IGNITION (281): NMT 0.2%

Change to read:

4.2 ORGANIC IMPURITIES

Mobile phase and Chromatographic system: Proceed as directed in the Assay.

System suitability solution: 0.6 mg/mL of Methsuximide in Mobile phase

Standard solution: 0.006 mg/mL of USP Methsuximide RS in Mobile phase

Sample solution: 6.0 mg/mL of Methsuximide in Mobile phase

System suitability

Sample: System suitability solution

Suitability requirements

Column efficiency: NLT (ERR 1-Sep-2022) 5800 theoretical plates

Tailing factor: NMT 1.3

Relative standard deviation: NMT 0.6%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of each impurity in the portion of Methsuximide taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response for each impurity from the Sample solution

r_S = peak response for methsuximide from the Standard solution

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

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

Acceptance criteria

Any individual impurity: NMT 0.1%

Total impurities: NMT 2.0%

5 SPECIFIC TESTS

LOSS ON DRYING (731)

Analysis: Dry a sample over phosphorus pentoxide for 16 h.

Acceptance criteria: NMT 0.5%

6 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in tight containers.

USP REFERENCE STANDARDS (11)

USP Methsuximide RS