Ciclopirox 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)

DOWNLOAD PDF HERE

1 DEFINITION

Ciclopirox Topical Solution contains NLT 90.0% and NMT 110.0% of the labeled amount of ciclopirox (C₁₂H₁₇NO₂).

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

[NOTE-Protect the Standard solution and Sample solution from light.]

Buffer: Transfer 5.25 g of citric acid and 25 mL of 0.1 M edetate disodium to a 1-L volumetric flask, and dilute with water to volume. Adjust with 8.5% diluted sodium hydroxide solution to a pH of 6.5.

Mobile phase: Acetonitrile and Buffer (35:65)

Standard solution: 0.2 mg/mL of USP Ciclopirox RS and 1 µg/mL each of USP Ciclopirox Related Compound B RS and USP Ciclopirox Related Compound C RS in methanol

Sample solution: Equivalent to 0.2 mg/mL of ciclopirox in methanol from Topical Solution. Pass through a filter of 0.45-µm pore size, and use the filtrate.

3.2 Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 303 nm

Column: 4-mm x 12.5-cm; 5-µm packing L1

Column temperature: 30 ± 5"

Flow rate: 0.9 mL/min

Run time: 5 times the retention time of the major peak

Injection size: 20 µL

3.3 System suitability

Sample: Standard solution

[NOTE-For information only, see Table 1 for relative retention times of impurities.]

3.4 Suitability requirements

Resolution: NLT 3.0 between ciclopirox and ciclopirox related compound B; and NLT 3.0 between ciclopirox related compound C and ciclopirox

Tailing factor: NMT 2.0 for the ciclopirox peak

Relative standard deviation: NMT 2.0% for the ciclopirox peak

3.5 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of ciclopirox (C₁₂H₁₇NO₂) in the portion of Topical Solution taken:

Result = (r_U/r_S) x (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 Ciclopirox RS in the Standard solution (mg/mL)

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

Acceptance criteria: 90.0%-110.0%

4 PERFORMANCE TESTS

MINIMUM FILL (755): Meets the requirement

5 IMPURITIES

ORGANIC IMPURITIES

Buffer, Mobile phase, Standard solution, Sample solution, Chromatographic system, and System suitability: Proceed as directed in the MICROBIAL ENUMERATION TESTS (61) and TESTS FOR SPECIFIED MICROORGANISMS (62): The total aerobic microbial count does not exceed 10² cfu / g and Assay.

Analysis

Sample: Sample solution

Calculate the percentage of each impurity in the portion of Topical Solution taken:

Result = (r_U/r_T) x (1/F) x 100

r_U = peak response of each individual impurity from the Sample solution 

r_T= sum of responses of all the peaks in the Sample solution 

F = relative response factor (see Table 1)

Acceptance criteria: See Table 1.

Table 1

^a Process impurity already monitored in the drug substance.

6 SPECIFIC TESTS

the total combined molds and yeasts count does not exceed 10¹ cfu / g

7 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in well-closed containers, protected from light. Store at controlled room temperature.

USP REFERENCE STANDARDS (11)

USP Ciclopirox RS

USP Ciclopirox Related Compound B. RS

6-Cyclohexyl-4-methyl-2-pyrone. 192.25

C₁₂H₁₆O₂

USP Ciclopirox Related Compound C RS

6-Cyclohexyl-4-methylpyridin-2(1H)-one. 191.27

C₁₂H₁₇NO