Ethionamide 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

Ethionamide Tablets contain NLT 95.0% and NMT 110.0% of the labeled amount of ethionamide (C₈H₁₀N₂S).

2 IDENTIFICATION

A.

Sample solution: The solution of Tablets employed for measurement of absorbance in the Assay

Acceptance criteria:

The Sample solution exhibits an absorbance maximum at 290 ± 2 nm.

B.

Sample solution: Nominally 20 mg/mL of ethionamide from digested powdered Tablets in methanol

Analysis: Filter the Sample solution through a sintered-glass funnel of medium pore size. Evaporate the filtrate on a steam bath to dryness.

Acceptance criteria: The residue so obtained melts at 155°–164°.

3 ASSAY

Procedure

Standard solution: 10 μg/mL of USP Ethionamide RS in methanol

Sample stock solution: Nominally 0.4 mg/mL of ethionamide prepared as follows. Transfer nominally 100 mg of ethionamide from powdered

Tablets (NLT 20), to a sintered-glass funnel of medium pore size that is fitted into a 250-mL suction flask. Extract the sample by stirring it with successive 10-mL portions of methanol, using a total of about 100 mL of solvent, and drawing off each portion of liquid with gentle suction before adding the next portion. Transfer the combined methanol extracts to a 250-mL volumetric flask, and dilute with methanol to volume.

Sample solution: Nominally 10 μg/mL of ethionamide in methanol from the Sample stock solution

Blank: Methanol

Instrumental conditions

Mode: UV

Analytical wavelength: 290 nm

Cell: 1 cm

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of ethionamide (C₈H₁₀N₂S) in the portion of Tablets taken:

Result = (A_U/A_S) × (C_S/C_U) × 100

A_U = absorbance of the Sample solution

A_S = absorbance of the Standard solution

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

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

Acceptance criteria: 95.0%–110.0%

4 PERFORMANCE TESTS

Dissolution 〈711〉

Medium: 0.1 N hydrochloric acid; 900 mL

Apparatus 1: 100 rpm

Time: 45 min

Detector: UV 274 nm

Standard solution: USP Ethionamide RS in Medium

Sample solution: Dilute with Medium to a concentration that is similar to that of the Standard solution.

Tolerances: NLT 75% (Q) of the labeled amount of ethionamide (C₈H₁₀N₂S) is dissolved.

Uniformity of Dosage Units 〈905〉: Meet the requirements

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers.

USP Reference Standards 〈11〉

USP Ethionamide RS