Fluorouracil Topical Solution

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

Fluorouracil Topical Solution contains NLT 90.0% and NMT 110.0% of the labeled amount of fluorouracil (C₄H₃FN₂O₂).

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.

B. The UV spectrum 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

Buffer: 6.8 g/L of monobasic potassium phosphate in water. Adjust with 5 M potassium hydroxide to a pH of 5.7 ± 0.1.

Mobile phase: Acetonitrile and Buffer (5:95)

Standard solution: 10 μg/mL of USP Fluorouracil RS in water

Sample stock solution: Nominally equivalent to 0.1 mg/mL of fluorouracil prepared as follows. Transfer a portion of Topical Solution, nominally equivalent to 10 mg of fluorouracil, into a 100-mL volumetric flask. Add 20 mL of methanol, and mix on a vortex mixer to dissolve.

Dilute with water to volume.

Sample solution: 10 μg/mL of fluorouracil in water, from Sample stock solution. Mix, and filter.

3.2 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 254 nm or diode array. [Note—Use the diode array detector to perform Identification test B.]

Column: 4.6-mm × 25-cm; 5-μm packing L1

Flow rate: 1 mL/min

Injection volume: 20 μL

3.3 System suitability

Sample: Standard solution

3.4 Suitability requirements

Relative standard deviation: NMT 0.73%, Standard solution

Tailing factor: NMT 1.5, Standard solution

3.5 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of fluorouracil (C₄H₃FN₂O₂) in the portion of Topical Solution taken:

Result = (r_U/r_S) × (C_S/C_U) × 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

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

C_U = nominal concentration of f;uorouracil in the Sample solution (μg/mL)

Acceptance criteria: 90.0%–110.0%

4 SPECIFIC TESTS

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

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers, and store at controlled room temperature.

USP Reference Standards 〈11〉

USP Fluorouracil RS