Sulfacetamide Sodium Topical Suspension

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

Sulfacetamide Sodium Topical Suspension contains NLT 90.0% and NMT 110.0% of the labeled amount of sulfacetamide sodium (C₈H₉N₂NaO₃S).

2 IDENTIFICATION

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

3 ASSAY

Procedure

Mobile phase: Methanol, glacial acetic acid, and water (125:3:875)

Internal standard solution: 5 mg/mL of sulfathiazole sodium

Standard stock solution: 0.25 mg/mL of USP Sulfacetamide Sodium RS and 0.1 mg/mL of p-hydroxybenzoic acid prepared as follows.

Transfer 25 mg of USP Sulfacetamide Sodium RS and 10 mg of p-hydroxybenzoic acid to a 100-mL volumetric flask. Dissolve in water, add 5 mL of the Internal standard solution, and dilute with water to volume.

Standard solution: 0.02 mg/mL of USP Sulfacetamide Sodium RS and 8 μg/mL of p-hydroxybenzoic acid in water from the Standard stock solution

Sample stock solution: Transfer 250 mg of Topical Suspension to a 125-mL conical flask, add 5 mL of the Internal standard solution, and dilute with 95 mL of water.

Sample solution: 2 mL of the Sample stock solution diluted with water to 25 mL. Centrifuge, and use the clear supernatant.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 254 nm

Column: 3.9-mm × 30-cm; packing L1

Flow rate: 2 mL/min

Injection volume: 20 μL

System suitability

Sample: Standard solution

[Note—The relative retention times for sulfanilamide, sulfacetamide, sulfathiazole, and p-hydroxybenzoic acid are about 0.2, 0.5, 1.0, and 1.2, respectively.]

Suitability requirements

Resolution: NLT 2.0 between sulfathiazole and p-hydroxybenzoic acid

Tailing factor: NMT 2

Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of anhydrous sulfacetamide sodium (C₈H₉N₂NaO₃S) in the portion of Topical Suspension taken:

Result = (R_U/R_S) × (C_S/C_U ) × 100

R_U = peak area ratio of sulfacetamide to sulfathiazole from the Sample solution

R_S = peak area ratio of sulfacetamide to sulfathiazole from the Standard solution

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

C_U = nominal concentration of sulfacetamide sodium in the Sample solution (mg/mL)

Acceptance criteria: 90.0%–110.0%

4 PERFORMANCE TESTS

Minimum Fill 〈755〉: Meets the requirements

5 SPECIFIC TESTS

Microbial Enumeration Tests 〈61〉andTests for Specified Microorganisms 〈62〉: The total aerobic microbial count does not exceed 102 cfu/mL, and the total combined molds and yeasts count does not exceed 50 cfu/mL. It meets the requirements of the test for Pseudomonas aeruginosa.

pH 〈791〉: 6.5–7.5

6 ADDITIONAL REQUIREMENTS

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

USP Reference Standards 〈11〉

USP Sulfacetamide Sodium RS