Dichlorphenamide 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

Dichlorphenamide Tablets contain NLT 92.0% and NMT 108.0% of the labeled amount of dichlorphenamide (C₆H₆Cl₂N₂O₄S₂).

2 IDENTIFICATION

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

Add the following:

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

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C.Identification Tests-General 〈191〉, Chemical Identification Tests, Sulfite

• Sample: Fuse a quantity of powdered Tablets, equivalent to 200 mg of dichlorphenamide, with 1 pellet of sodium hydroxide.
• Acceptance criteria: The ammonia fumes produced cause moistened red litmus paper to turn blue. The fusion mixture meets the requirements of the test for Sulfite.

3 ASSAY

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3.1 Procedure

Solution A: 2.4 g/L of monobasic sodium phosphate and 2.8 g/L of dibasic sodium phosphate in water

Solution B: Acetonitrile

Mobile phase: See Table 1.

Table 1

Diluent: Acetonitrile and water (1:1)

Standard solution: 0.5 mg/mL of USP Dichlorphenamide RS in Diluent. Sonicate if necessary.

Sample stock solution: Nominally 1 mg/mL of dichlorphenamide in Diluent prepared as follows. Transfer NLT 20 finely powdered Tablets, equivalent to 100 mg of dichlorphenamide, to a 100-mL volumetric flask. Fill the flask with 80 mL of Diluent, sonicate for 5 min, and mechanically shake for at least 30 min. Dilute with Diluent to volume, and centrifuge for 10 min.

Sample solution: Nominally 0.5 mg/mL of dichlorphenamide in Diluent from Sample stock solution

Chromatographic system

• (See Chromatography 〈621〉, System Suitability.)
• Mode: LC
• Detector: UV 280 nm. For Identification B, use a diode array detector in the range of 220–400 nm.
• Column: 4.6-mm × 15-cm; 2.7-µm packing L1
• Flow rate: 0.4 mL/min
• Injection volume: 10 µL
• System suitability
• Sample: Standard solution
• Suitability requirements
• Tailing factor: NMT 2.0
• Relative standard deviation: NMT 1.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of dichlorphenamide (C₆H₆Cl₂N₂O₄S₂) in the portion of Tablets taken:

Result = (rᵤ/rₛ) × (Cₛ/Cᵤ) × 100

rᵤ = peak response from the Sample solution

rₛ = peak response from the Standard solution

Cₛ = concentration of USP Dichlorphenamide RS in the Standard solution (mg/mL)

Cᵤ = nominal concentration of dichlorphenamide in the Sample solution (mg/mL) 

Acceptance criteria: 92.0%–108.0%

4 PERFORMANCE TESTS

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4.1 Dissolution 〈711〉

Medium: 0.1 M pH 8.0 phosphate buffer (see Reagents, Indicators, and Solutions-Buffer Solutions); 900 mL

Apparatus 2: 75 rpm

Time: 60 min

Standard solution: USP Dichlorphenamide RS in Medium

Sample solution: Use filtered portions of the solution under test, suitably diluted with Medium in comparison with the Standard solution.

Instrumental conditions

• Mode: UV
• Analytical wavelength: Maximum absorbance at about 285 nm

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of dichlorphenamide (C₆H₆Cl₂N₂O₄S₂) dissolved:

Result = (Aᵤ/Aₛ) × Cₛ × D × (V/L) × 100

Aᵤ = absorbance of the Sample solution

Aₛ = absorbance of the Standard solution

Cₛ = concentration of the Standard solution (mg/mL)

D = dilution factor for the Sample solution, if needed

V = volume of Medium, 900 mL

L = label claim (mg/Tablet)

Tolerances: NLT 80% (Q) of the labeled amount of dichlorphenamide (C₆H₆Cl₂N₂O₄S₂) is dissolved.

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

5 IMPURITIES

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5.1 Organic Impurities

Solution A, Solution B, Diluent, and Chromatographic system: Proceed as directed in the Assay.

Standard solution: 0.004 mg/mL of USP Dichlorphenamide RS in Diluent

Sample solution: Nominally 2 mg/mL of dichlorphenamide in Diluent prepared as follows. Transfer NLT 20 finely powdered Tablets, equivalent to 50 mg of dichlorphenamide, to a 25-mL volumetric flask. Fill the flask with 20 mL of Diluent. Sonicate for 5 min and mechanically shake for at least 30 min. Dilute with Diluent to volume, and centrifuge for 10 min.

System suitability

• Sample: Standard solution
• Suitability requirements
• Tailing factor: NMT 1.5
• Relative standard deviation: NMT 5.0%

Analysis

Samples: Standard solution and Sample solution

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

Result = (rᵤ/rₛ) × (Cₛ/Cᵤ) × 100

rᵤ = peak response of each individual degradation product from the Sample solution

rₛ = peak response of dichlorphenamide from the Standard solution

Cₛ = concentration of USP Dichlorphenamide RS in the Standard solution (mg/mL)

Cᵤ = nominal concentration of dichlorphenamide in the Sample solution (mg/mL)

Acceptance criteria

• Individual degradation product: NMT 0.20%
• Total degradation products: NMT 1.0%

6 ADDITIONAL REQUIREMENTS

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Packaging and Storage: Preserve in well-closed containers. Store at controlled room temperature.

USP Reference Standards <11>

USP Dichlorphenamide RS