Acepromazine Maleate

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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C₁₉H₂₂N₂OS·C₄H₄O₄ 442.53

Ethanone, 1-[10-[3-(dimethylamino)propyl]-10H-phenothiazin-2-yl]-, (Z)-2-butenedioate (1:1);

10-[3-(Dimethylamino)propyl]phenothiazin-2-yl methyl ketone maleate (1:1) CAS RN®: 3598-37-6; UNII: 37862HP20M.

1 DEFINITION

Acepromazine Maleate contains NLT 98.0% and NMT 101.0% of acepromazine maleate (C₁₉H₂₂N₂OS·C₄H₄O₄), calculated on the anhydrous basis.

Throughout the following procedures, protect samples, the USP Reference Standard, and solutions containing them, by conducting the procedures without delay, under subdued light, or using low-actinic glassware.

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 for acepromazine of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

3.1 PROCEDURE

Buffer: Add 6 mL of triethylamine to 700 mL of water, and adjust with phosphoric acid to a pH of 2.5.

Mobile phase: Acetonitrile and Buffer (300:700)

Standard stock solution: 1 mg/mL of USP Acepromazine Maleate RS in 0.05 N hydrochloric acid

Standard solution: 0.1 mg/mL of USP Acepromazine Maleate RS in water from Standard stock solution

Sample stock solution: 1 mg/mL of Acepromazine Maleate in 0.05 N hydrochloric acid

Sample solution: 0.1 mg/mL of Acepromazine Maleate in water from Sample stock solution

3.2 Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 280 nm

Column: 4-mm x 15-cm; 5-µm packing L7

Flow rate: 1 mL/min

Injection volume: 10 µL

3.3 System suitability

Sample: Standard solution

Suitability requirements

Column efficiency: NLT 1500 theoretical plates

Tailing factor: NMT 2.5

Relative standard deviation: NMT 2.0%

3.4 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of acepromazine maleate (C₁₉H₂₂N₂OS·C₄H₄O₄) in the portion of Acepromazine Maleate taken:

Result = (r_U/r_S) x (C_S/C_U) × 100

r_U = peak area response from the Sample solution

r_S = peak area response from the Standard solution

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

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

Acceptance criteria: 98.0%–101.0% on the anhydrous basis

4 IMPURITIES

4.1 RESIDUE ON IGNITION (281)

NMT 0.2%

4.2 ORGANIC IMPURITIES

Conduct this test without exposure to daylight, and with the minimum necessary exposure to artificial light.

Diluent: Methanol and diethylamine (19:1)

Sample solution: 20.0 mg/mL of Acepromazine Maleate in Diluent

Standard solution: 0.1 mg/mL of Acepromazine Maleate in Diluent from the Sample solution

4.2.1 Chromatographic system

(See Chromatography (621), Thin-Layer Chromatography.)

Mode: TLC

Adsorbent: 0.25-mm layer of chromatographic silica gel mixture

Application volume: 10 µL

Developing solvent system: n-Heptane, isobutyl alcohol, and diethylamine (75:17:8)

4.2.2 Analysis

Samples: Standard solution and Sample solution

Develop the chromatogram in the Developing solvent system until the solvent front has moved three-fourths the length of the plate.

Remove the plate from the chamber and allow to air dry. Examine the plate under short-wavelength UV light.

Acceptance criteria: 0.5%; no spot, other than the principal acepromazine spot and any at the origin, observed in the chromatogram of the Sample solution is more intense than the principal spot observed in the chromatogram of the Standard solution.

5 SPECIFIC TESTS

5.1 MELTING RANGE OR TEMPERATURE (741)

136°-139°

5.2 PH (791)

Sample solution: 10 mg/mL of Acepromazine Maleate in water

Acceptance criteria: 4.0-5.5

5.3 WATER DETERMINATION, Method (921)

NMT 1.0%

6 ADDITIONAL REQUIREMENTS

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

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

USP REFERENCE STANDARDS (11)

USP Acepromazine Maleate RS