Amprolium

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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Amprolium

C₁₄H₁₉ClN₄·HCl 315.24

1-[(4-Amino-2-propyl-5-pyrimidinyl)methyl]-2-methylpyridinium chloride monohydrochloride;

1-[(4-Amino-2-propyl-5-pyrimidinyl)methyl]-2-picolinium chloride monohydrochloride

CAS RN®: 137-88-2; UNII: 95CO6N199Q.

1 DEFINITION

Amprolium contains NLT 97.0% and NMT 101.0% of amprolium (C₁₄H₁₉ClN₄·HCl), calculated on the dried basis.

2 IDENTIFICATION

Change to read:

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

Sample: Previously dried

Acceptance criteria: Meets the requirements

Change to read:

B. ▲Spectroscopic Identification Tests 〈197〉, Ultraviolet-Visible Spectroscopy: 197U▲ (CN 1-May-2020)

Analytical wavelength: 246 nm

Sample solution: 10 µg/mL in 0.1 N hydrochloric acid

Acceptance criteria: Absorptivities, calculated on the dried basis, do not differ by more than 3.0%.

3 ASSAY

Procedure

Diluent: Methanol, acetonitrile, and water (45:5:50)

Mobile phase: 6 g of sodium 1-heptanesulfonate in 500 mL of water. Add 12 mL of glacial acetic acid, 2.0 mL of triethylamine, 450 mL of methanol, and 50 mL of acetonitrile. Pass through a suitable filter of 0.5-µm or finer pore size.

System suitability solution: 0.5 mg/mL of USP Amprolium RS and 0.2 mg/mL of 2-picoline in Diluent

Standard solution: 0.5 mg/mL of USP Amprolium RS in Diluent

Sample solution: 0.5 mg/mL of Amprolium in Diluent

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 254 nm

Column: 4.6-mm × 25-cm; packing L13

Flow rate: 0.6 mL/min

Injection volume: 10 µL

System suitability

Sample: System suitability solution

Suitability requirements

Resolution: NLT 7 between amprolium and 2-picoline

Column efficiency: NLT 6500 theoretical plates from the amprolium peak

Tailing factor: NMT 2.3 for the amprolium peak

Relative standard deviation: NMT 1.0% for amprolium

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of amprolium (C₁₄H₁₉ClN₄·HCl) in the portion of Amprolium taken:

Result = (r₁/r₂) × (C₁/C₂) × 100

r₁ = peak response from the Sample solution

r₂ = peak response from the Standard solution

C₁ = concentration of USP Amprolium RS in the Standard solution (mg/mL)

C₂ = concentration of Amprolium in the Sample solution (mg/mL)

Acceptance criteria: 97.0%–101.0% on the dried basis

4 SPECIFIC TESTS

Loss on Drying 〈731〉

Analysis: Dry a sample at a pressure not exceeding 5 mm of mercury at 100° for 3 h.

Acceptance criteria: NMT 1.0%

5 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in well-closed containers.

Labeling: Label it to indicate that it is for veterinary use only.

USP Reference Standards 〈11〉

USP Amprolium RS