Ensulizole

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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1H-Benzimidazole-5-sulfonic acid-2-phenyl-;

2-Phenylbenzimidazole-5-sulfonic acid CAS RN®: 27503-81-7; UNII: 9YQ9DI1W42.

1 DEFINITION

Ensulizole contains NLT 98.0% and NMT 102.0% of ensulizole (C₁₃H₁₀N₂O₃S), calculated on the dried basis.

2 IDENTIFICATION

A. SPECTROSCOPIC IDENTIFICATION TESTS (197), infrared Spectroscopy: 197K or 1974

Change to read:

of the Standard solution, as obtained in B. The retention time of the major peak of the Sample solution corresponds to that (ERR 1-Apr-2024) Of1 the Assay.

3 ASSAY

PROCEDURE

Solution A: 1 mL/L of trifluoroacetic acid in water

Solution B: 0.5 mL/L of trifluoroacetic acid in acetonitrile

Diluent: Dimethylformamide and water (20:80)

Mobile phase: See Table 1.

Standard solution: 0.04 mg/mL of USP Ensulizole RS in Diluent. Sonication may be necessary for complete dissolution.

Sample solution: 0.04 mg/ml. of Ensulizole in Diluent. Sonication may be necessary for complete dissolution.

Chromatographic system

(See Chromatography (621), System Suitability,)

Mode: LC

Detector: UV 300 nm

Column: 4.6-mm x 25-cm; 5-um packing L1

Flow rate: 1 mL/min

Injection volume: 20 μL.

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 0.73%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of ensulizole (C₁₃H₁₀N₂O₃S) in the portion of Ensulizole taken:

Result = (r_U/(r_S) × (C_S /C_U) x 100

r_U = peak response of ensulizole from the Sample solution

r_S = peak response of ensulizole from the Standard solution

C_S = concentration of USP Ensulizole  RS in the Standard solution (mg/ml)

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

Acceptance criteria: 98.0%-102.0% on the dried basis

4 SPECIFIC TESTS

LOSS ON DEVING (731)

Analysis: Dry at 105° for 4 h.

Acceptance criteria: NMT 2.0%

5 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in tight containers in a cool place.