Pramoxine Hydrochloride

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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C₁₇H₂₇NO₃  · HCl 329.86

Morpholine, 4-[3-(4-butoxyphenoxy)propyl]-, hydrochloride;

4-[3-(p-Butoxyphenoxy)propyl]morpholine hydrochloride CAS RN®: 637-58-1; UNII: 88AYB867L5.

1 DEFINITION

Pramoxine Hydrochloride contains NLT 98.0% and NMT 102.0% of pramoxine hydrochloride (C₁₇H₂₇NO₃ · HCl), calculated on the dried basis.

2 IDENTIFICATION

Change to read:

A. Spectroscopic Identification Tests 〈197〉, Infrared Spectroscopy: 197K (CN 1-May-2020)

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

C. Identification Tests—General, Chloride〈191〉: Meets the requirements

3 ASSAY

Procedure

Buffer: Dissolve 8.71 g of dibasic potassium phosphate in about 800 mL of water, adjust with dilute phosphoric acid (1 in 10) to a pH of 7.5 ± 0.1, and add water to make 1000 mL.

Mobile phase: Acetonitrile and Buffer (55:45)

Standard solution: 0.5 mg/mL of USP Pramoxine Hydrochloride RS in Mobile phase

Sample solution: 0.5 mg/mL of Pramoxine Hydrochloride in Mobile phase

3.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 224 nm

Column: 4.6-mm × 25-cm; packing L1

Column temperature: 40°

Flow rate: 2 mL/min

Injection volume: 20 µL

3.2 System suitability

Sample: Standard solution

Suitability requirements

Column efficiency: NLT 1500 theoretical plates

Tailing factor: NMT 1.5

Relative standard deviation: NMT 1.5%

3.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of pramoxine hydrochloride (C₁₇H₂₇NO₃ · HCl) in the portion of Pramoxine Hydrochloride 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 Pramoxine Hydrochloride RS in the Standard solution (mg/mL)

C_U = concentration of Pramoxine Hydrochloride in the Sample solution (mg/mL)

Acceptance criteria: 98.0%–102.0% on the dried basis

4 IMPURITIES

Residue on Ignition 〈281〉: NMT 0.1%

5 SPECIFIC TESTS

Melting Range or Temperature 〈741〉: 170°–174°

Loss on Drying 〈731〉

Analysis: Dry at 105° for 1 h.

Acceptance criteria: NMT 1.0%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers.

USP Reference Standards 〈11〉

USP Pramoxine Hydrochloride RS