Hexylresorcinol Lozenges

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

Hexylresorcinol Lozenges contain NLT 90.0% and NMT 110.0% of the labeled amount of hexylresorcinol (C₁₂H₁₈O₂).

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

Procedure

Buffer: Dissolve 3.4 g of monobasic potassium phosphate in 850 mL of water. Adjust with phosphoric acid to a pH of 3.0 ± 0.05, dilute with water to 1000 mL, mix, and pass through a suitable filter of 0.5-µm or finer pore size.

Mobile phase: Methanol and Buffer (65:35)

Internal standard solution: 0.25 mg/mL of hexanophenone in Mobile phase 

Standard stock solution: 0.4 mg/mL of USP Hexylresorcinol RS in Mobile phase 

Standard solution: Transfer 10.0 mL of Standard stock solution and 10.0 mL of Internal standard solution to a 50-mL volumetric flask, and dilute with Mobile phase to volume. This solution contains 0.08 mg/mL of USP Hexylresorcinol RS. 

Sample solution: Nominally 0.08 mg/mL of hexylresorcinol prepared as follows. Transfer the equivalent to 4 mg of hexylresorcinol from Lozenges (NLT 20 Lozenges, weighed and pulverized) to a 50-mL volumetric flask. Add 10.0 mL of Internal standard solution and 20 mL of Mobile phase, and shake until dissolved. Dilute with Mobile phase to 50 mL, and mix. Pass a portion of this solution through a suitable lter of 0.5-µm or finer pore size, and use the filtrate. 

3.1 Chromatographic system 

(See Chromatography 〈621〉, System Suitability.) 

Mode: LC 

Detector: UV 280 nm 

Column: 4.6-mm × 15-cm; packing L7 

Column temperature: 37 ± 2° 

Flow rate: 1.5 mL/min 

Injection volume: 10 µL 

3.2 System suitability 

Samples: Standard solution and Sample solution 

[Note—The relative retention times for hexylresorcinol and hexanophenone are 0.6 and 1.0, respectively.] 

Suitability requirements 

Resolution: NLT 1.2 between the hexylresorcinol peak and the nearest adjacent peak, Sample solution 

Column efficiency: NLT 1500 theoretical plates, Standard solution 

Tailing factor: 0.9–1.4, Standard solution 

Relative standard deviation: NMT 2.0%, Standard solution 

3.3 Analysis 

Samples: Standard solution and Sample solution 

Calculate the percentage of the labeled amount of hexylresorcinol (C₁₂H₁₈O₂) in the portion of Lozenges taken: 

Result = (R_U /R_S ) × (C_S /C_U ) × 100  

R_U = peak response ratio of hexylresorcinol to hexanophenone in the Sample solution 

R_S = peak response ratio of hexylresorcinol to hexanophenone in the Standard solution 

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

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

Acceptance criteria: 90.0%–110.0%

4 PERFORMANCE TESTS

Uniformity of Dosage Units 〈905〉: Meet the requirements

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers.

USP Reference Standards 〈11〉

USP Hexylresorcinol RS