Methazolamide

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

Methazolamide contains NLT 98.0% and NMT 102.0% of methazolamide (C₅H₈N₄O₃S₂), calculated on the dried basis.

2 IDENTIFICATION

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197K

B. Spectroscopic Identification Tests 〈197〉, Ultraviolet-Visible Spectroscopy: 197U

Sample solution: 10 μg/mL of Methazolamide in 0.1 N sodium hydroxide solution

Acceptance criteria: Meets the requirements

3 ASSAY

Change to read:

Procedure

Buffer solution: 1.80 g/L of anhydrous sodium acetate in water. Adjust, if necessary, with glacial acetic acid to a pH of 4.5. (USP 1-Aug-2022)

Mobile phase: Acetonitrile and Buffer solution (14:86)

System suitability stock solution: 0.3 mg/mL of USP Acetaminophen RS (USP 1-Aug-2022) and 0.5 mg/mL of USP Methazolamide RS in acetonitrile

System suitability solution: 30 μg/mL of USP Acetaminophen RS (USP 1-Aug-2022) and 50 μg/mL of USP Methazolamide RS in Buffer solution from the System suitability stock solution

Standard stock solution: 0.1 mg/mL of USP Methazolamide RS prepared as follows. Dissolve 20 mg of USP Methazolamide RS in 20 mL of acetonitrile contained in a 200-mL volumetric flask and dilute with Buffer solution to volume.

Standard solution: 50 μg/mL of USP Methazolamide RS in Buffer solution from the Standard stock solution

Sample stock solution: 0.5 mg/mL of Methazolamide prepared as follows. Dissolve 100 mg of Methazolamide in 20 mL of acetonitrile contained in a 200-mL volumetric flask and dilute with Buffer solution to volume.

Sample solution: 50 μg/mL of Methazolamide in Buffer solution from the Sample stock solution

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 265 nm

Column: 3.9-mm × 15.0-cm; 10-μm (USP 1-Aug-2022) packing L1

Flow rate: 1.5 mL/min

Injection volume: 10 μL

Run time: NLT 5 times the retention time of methazolamide (USP 1-Aug-2022)

System suitability

Samples: System suitability solution and Standard solution

[Note—The relative retention times for acetaminophen and methazolamide are 0.6 and 1.0, respectively.]

Suitability requirements

Resolution: NLT 4.0 between acetaminophen and methazolamide, System suitability solution

Tailing factor: NMT 2.0 for methazolamide, System suitability solution

Relative standard deviation: NMT 0.73%, (USP 1-Aug-2022) Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of methazolamide (C₅H₈N₄O₃S₂) in the portion of Methazolamide taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response of methazolamide from the Sample solution

r_S = peak response of methazolamide from the Standard solution

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

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

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

4 IMPURITIES

Residue on ignition 〈281〉: NMT 0.1%

Delete the following:

Selenium 〈291〉

Sample: 200 mg

Acceptance criteria: NMT 0.003% (USP 1-Aug-2022)

5 SPECIFIC TESTS

Loss on drying 〈731〉

Analysis: Dry at 105° for 2 h.

Acceptance criteria: NMT 0.5%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed, light-resistant containers.

Change to read:

USP Reference standards 〈11〉

USP Acetaminophen RS (USP 1-Aug-2022)

USP Methazolamide RS