Riluzole Tablets

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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1 DEFINITION

Riluzole Tablets contain NLT 90.0% and NMT 110.0% of the labeled amount of riluzole (C₈H₅F₃N₂OS).

2 IDENTIFICATION

A. The UV spectrum of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

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 (45:55)

Standard solution: 0.05 mg/mL of USP Riluzole RS in Mobile phase

Sample stock solution: Nominally 0.5 mg/mL of riluzole prepared as follows. Transfer an equivalent to 50 mg of riluzole, from finely powdered Tablets (NLT 20), to a 100-mL volumetric flask, add 80 mL of Mobile phase, sonicate for about 10 min, and stir for another 10 min. Dilute with Mobile phase to volume.

Sample solution: Nominally 0.05 mg/mL of riluzole in Mobile phase, prepared from the Sample stock solution. Pass this solution through a filter of 0.45-µm pore size, and discard the first 5 mL of filtrate. Use the filtrate for analysis. [Note—A PVDF or equivalent filter may be suitable.]

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 221 nm. For Identification A, use a diode array detector in the range of 200–400 nm.

Column: 4.6-mm × 15-cm; 5-µm packing L1

Flow rate: 1 mL/min

Injection volume: 20 µL

Run time: NLT 2 times the retention time of the riluzole peak

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of riluzole (C₈H₅F₃N₂OS) in the portion of Tablets 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 Riluzole RS in the Standard solution (mg/mL)

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

Acceptance criteria: 90.0%–110.0%

4 PERFORMANCE TESTS

4.1 Dissolution 〈711〉

Medium: 0.1 N hydrochloric acid VS; 900 mL, deaerated

Apparatus 2: 50 rpm

Time: 30 min

Standard solution: 0.05 mg/mL of USP Riluzole RS in Medium

Sample solution: Pass a portion of the solution under test through a suitable filter of 0.45-µm pore size.

Instrumental conditions

Mode: UV

Analytical wavelength: 254 nm

Cell: 0.5 cm

Blank: Medium

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of riluzole (C₈H₅F₃N₂OS) dissolved:

Result = (A_U/A_S) × (C_S × V/L) × 100

A_U = absorbance of the Sample solution

A_S = absorbance of the Standard solution

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

V = volume of Medium, 900 mL

L = label claim (mg/Tablet)

Tolerances: NLT 80% (Q) of the labeled amount of riluzole (C₈H₅F₃N₂OS) is dissolved.

4.2 Uniformity of Dosage Units 〈905〉: Meet the requirements

5 IMPURITIES

5.1 Organic Impurities

Mobile phase, Sample stock solution, and Chromatographic system: Proceed as directed in the Assay.

System suitability solution: 500 µg/mL of USP Riluzole RS and 0.5 µg/mL of USP Riluzole Related Compound A RS in Mobile phase

Standard solution: 2.5 µg/mL of USP Riluzole RS in Mobile phase, prepared from the Standard solution in the Assay

Sample solution: Prepare as directed in the Sample stock solution.

System suitability

Samples: System suitability solution and Standard solution

Suitability requirements

Resolution: NLT 1.5 between riluzole and riluzole related compound A, System suitability solution

Tailing factor: NMT 2.0, Standard solution

Relative standard deviation: NMT 2.0%, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of each degradation product in the portion of Tablets taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of each degradation product from the Sample solution

r_S = peak response of riluzole from the Standard solution

C_S = concentration of USP Riluzole RS in the Standard solution (µg/mL)

C_U = nominal concentration of riluzole in the Sample solution (µg/mL)

Acceptance criteria

Any individual degradation product: NMT 0.2%

Total degradation products: NMT 1.0%

6 ADDITIONAL REQUIREMENTS

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

Change to read:

USP Reference Standards 〈11〉

USP Riluzole RS

USP Riluzole Related Compound A RS

4-(Trifluoromethoxy)aniline. (ERR 1-Apr-2021)

C₇H₆F₃NO  177.13 (ERR 1-Apr-2021)