Naftifine Hydrochloride Gel

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

Naftifine Hydrochloride Gel contains NLT 90.0% and NMT 110.0% of the labeled amount of naftifine hydrochloride (C₂₁H₂₁N · HCl) in a water-miscible base.

2 IDENTIFICATION

A. 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

3.1 Procedure

Mobile phase: n-Hexane, alcohol, dimethylformamide, and formic acid (200:60:40:2). Cover tightly with a moisture-proof film, and allow to stand for 12 h at room temperature.

Standard solution: 0.2 mg/mL of USP Naftifine Hydrochloride RS in Mobile phase

Sample solution: Transfer 1000 mg of Gel to a 100-mL volumetric flask. Dissolve in 60 mL of methanol, mix vigorously for 2 min, and dilute with methanol to volume. Heat at 45° for 5 min, and cool to room temperature.

Chromatographic system

• (See Chromatography 〈621〉, System Suitability.)
• Mode: LC
• Detector: UV 270 nm
• Column: 4.6-mm × 25-cm; 5-µm packing L3
• Flow rate: 2 mL/min
• Injection volume: 20 µL

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of naftifine hydrochloride (C₂₁H₂₁N · HCl) in the portion of Gel 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 Naftifine Hydrochloride RS in the Standard solution (mg/mL)

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

Acceptance criteria: 90.0%–110.0%

4 PERFORMANCE TESTS

Minimum Fill 〈755〉: Meets the requirements

5 SPECIFIC TESTS

5.1 Content of Alcohol

Internal standard solution: Transfer 10.0 mL of n-propyl alcohol to a 200-mL volumetric flask, and dilute with water to volume.

Standard stock solution: 10.0 mg/mL of alcohol

Standard solution: Transfer 3.0 mL of Internal standard solution to a 10-mL volumetric flask, and dilute with Standard stock solution to volume.

Sample solution: Transfer 250 mg of Gel to a suitable container. Add 14.0 mL of water and 6.0 mL of Internal standard solution, and shake for 15 min.

Chromatographic system

• (See Chromatography 〈621〉, System Suitability.)
• Mode: GC
• Detector: Flame ionization
• Column: 3.2-mm × 1.5-m; 80- to 100-mesh support S3
• Temperatures
• Injector: 200°
• Column: 170°
• Detector: 200°
• Carrier gas: Nitrogen
• Flow rate: 45 mL/min
• Injection volume: 1 µL

System suitability

• Sample: Standard solution
• Suitability requirements
• Resolution: NLT 2.0 between alcohol and the internal standard
• Capacity factor, k′: 2.0–3.5 for alcohol and 6.0–8.0 for the internal standard
• Tailing factor: NMT 2.5
• Relative standard deviation: NMT 2.5%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of alcohol (C₂H₅OH) in the portion of Gel taken:

Result = (Rᵤ / Rₛ) × (Cₛ / Cᵤ) × 100

Rᵤ = peak response ratio of alcohol to the internal standard from the Sample solution

Rₛ = peak response ratio of alcohol to the internal standard from the Standard solution

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

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

Acceptance criteria: 40%–45%

Microbial Enumeration Tests 〈61〉 and Tests for Specified Organisms 〈62〉: It meets the requirements of the tests for absence of Staphylococcus aureus and Pseudomonas aeruginosa.

pH 〈791〉: 5.5–7.5

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers.

USP Reference Standards 〈11〉

USP Naftifine Hydrochloride RS