Tinidazole

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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C₈H₁₃N₃O₄S          247.27

1H-Imidazole, 1-[2-(ethylsulfonyl)ethyl]-2-methyl-5-nitro-;

1-[2-(Ethylsulfonyl)ethyl]-2-methyl-5-nitroimidazole     CAS RN^®: 19387-91-8; UNII: 033KF7V46H.

1 DEFINITION

Tinidazole contains NLT 98.0% and NMT 102.0% of tinidazole (C₈H₁₃N₃O₄S), calculated on the dried 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 Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

PROCEDURE

Mobile phase: Acetonitrile, methanol, and water (10:20:70)

Standard solution: 0.1 mg/mL of USP Tinidazole RS prepared as follows. Transfer a suitable amount of USP Tinidazole RS to a suitable volumetric flask and add methanol to 10% of the final volume of the flask. Dilute with Mobile phase to volume.

Sample solution: 0.1 mg/mL of Tinidazole prepared as follows. Transfer a suitable amount of Tinidazole to a suitable volumetric flask and add methanol to 10% of the final volume of the flask. Dilute with Mobile phase to volume.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 320 nm

Column: 3.0-mm x 25-cm; 5-µm packing L7

Flow rate: 0.5 mL/min

Injection volume: 20 µL

Run time: 1.5 times the retention time of tinidazole

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 1.5

Relative standard deviation: NMT 0.73%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of tinidazole (CHNOS) in the portion of Tinidazole taken:

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

r_U = peak response of tinidazole from the Sample solution

r_S = peak response of tinidazole from the Standard solution

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

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

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

4 IMPURITIES

4.1 RESIDUE ON IGNITION (281)

NMT 0.1%

4.2 ORGANIC IMPURITIES

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

Standard stock solution 1: Use the Standard solution from the Assay.

Standard stock solution 2: 0.05 mg/mL each of USP Tinidazole Related Compound A RS and USP Tinidazole Related Compound B RS prepared as follows. Transfer suitable amounts of USP Tinidazole Related Compound A RS and USP Tinidazole Related Compound B RS to a suitable volumetric flask and add methanol to 10% of the final volume of the flask. Dilute with Mobile phase to volume.

Standard solution: 0.1 µg/mL of USP Tinidazole RS and 0.2 µg/mL each of USP Tinidazole Related Compound A RS and USP Tinidazole Related Compound B RS in Mobile phase from Standard stock solution 1 and Standard stock solution 2

System suitability

Sample: Standard solution

Suitability requirements

Resolution: NLT 2.0 between tinidazole related compound A and tinidazole related compound B

Relative standard deviation: NMT 5.0% for each peak

Analysis

Samples: Sample solution and Standard solution

Calculate the percentages of tinidazole related compound A and tinidazole related compound B in the portion of Tinidazole taken:

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

r_U = peak response of tinidazole related compound A or tinidazole related compound B from the Sample solution

r_S = peak response of tinidazole related compound A or tinidazole related compound B from the Standard solution

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

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

Calculate the percentage of any unspecified impurity in the portion of Tinidazole taken:

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

r_U = peak response of each unspecified impurity from the Sample solution

r_S = peak response of tinidazole from the Standard solution

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

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

Acceptance criteria: See Table 1. Disregard any peak less than 0.05%.

Table 1

5 SPECIFIC TESTS

LOSS ON DRYING (731)

Analysis: Dry at 100° -105° to constant weight.

Acceptance criteria: NMT 0.5%

6 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in tight containers, protected from light, at controlled room temperature.

USP REFERENCE STANDARDS (11)

USP Tinidazole RS

USP Tinidazole Related Compound A RS

2-Methyl-5-nitroimidazole.

C₄H₅N₃O₂            127.10

USP Tinidazole Related Compound B. RS

1-(2-Ethyl-sulfonylethyl)-2-methyl-4-nitroimidazole.

C₈H₁₃N₃O₄S         247.28