Xylazine

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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C₁₂H₁₆N₂S       220.33

4H-1,3-Thiazin-2-amine, N-(2,6-dimethylphenyl)-5,6-dihydro-; 5,6-Dihydro-2-(2,6-xylidino)-4H-1,3-thiazine CAS RN: 7361-61-7; UNII: 2KFG9TP5V8.

1 DEFINITION

Xylazine contains NLT 98.0% and NMT 102.0% of xylazine (C₁₂H₁₆N₂S).

2 IDENTIFICATION

Change to read:

A. SPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 197A or 197K _{(CN 1-MAY-2020)}

Change to read:

B.SPECTROSCOPIC IDENTIFICATION TESTS (197), Ultraviolet-Visible Spectroscopy: 197U _{(CN 1-MAY-2020)}

Sample solution: 5 µg/mL in 0.1 N hydrochloric acid

Acceptance criteria: Meets the requirements

3 ASSAY

PROCEDURE

Solution A: Dissolve 3.03 g of sodium 1-heptanesulfonate in 800 mL of water, adjust with 2 N sulfuric acid to a pH of 3.0, and dilute with water to 1000 mL.

Pass through a filter of 0.5-µm or finer pore size.

Solution B: Acetonitrile

Diluent: Solution A and Solution B (50:50)

Mobile phase: See Table 1. Return to original conditions, and equilibrate the system.

Table 1

Standard solution: 0.4 mg/mL of USP Xylazine RS in Diluent

Sample solution: 0.4 mg/mL of Xylazine in Diluent

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 226 nm

Column: 3.9-mm × 30-cm; packing L1

Flow rate: 1 mL/min

Injection volume: 10 µL

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of xylazine (C₁₂H₁₆N₂S) in the portion of Xylazine 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 Xylazine RS in the Standard solution (mg/mL)

C_u = concentration of Xylazine in the Sample solution (mg/mL)

Acceptance criteria: 98.0%–102.0%

4 IMPURITIES

RESIDUE ON IGNITION (281): NMT 0.1%

4.1 LIMIT OF 3-AMINO-1-PROPANOL

Standard solution: 0.5 mg/mL of 3-amino-1-propanol in methanol

Sample solution: 100 mg/mL of Xylazine in methanol, Sonicate to dissolve.

Chromatographic system

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

Mode: TLC

Adsorbent: 0.25-mm layer of chromatographic silica gel

Application volume: 5 µL

Developing solvent system: Alcohol and ammonium hydroxide (80:20)

Spray reagent: 2 mg/mL of ninhydrin in alcohol

Analysis

Samples: Standard solution and Sample solution

Develop the chromatogram in a saturated chromatographic chamber containing the Developing solvent system until the solvent front has moved three-fourths of the length of the plate. Remove the plate from the chromatographic chamber, mark the solvent front, and air-dry the plate. Spray the plate with the Spray reagent, and immediately heat the plate in an oven at 105". When the spots are visible, remove the plate from the oven, and allow to cool.

Acceptance criteria: The intensity of the spot for 3-amino-1-propanol from the Sample solution is not greater than that of the spot for 3-amino-1-propanol from the Standard solution (0.5%).

4.2 LIMIT OF ACETONE AND ISOPROPYL ALCOHOL

Proceed as directed in Residual Solvents (467).

Acceptance criteria

Acetone: NMT 0.02%.

Isopropyl alcohol: NMT 0.2%

4.3 ORGANIC IMPURITIES

Solution A, Solution B, and Diluent: Prepare as directed in the Assay.

Mobile phase: See Table 2. Return to original conditions, and equilibrate the system.

Table 2

Sample solution: Transfer 100 mg of Xylazine into a 10-mL volumetric ask, add 5.0 mL of Solution B, and swirl to dissolve. Add 4 mL of Solution A, and swirl. Dilute with Solution A to volume, and mix.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 205 nm

Column: 4.6-mm × 25-cm; packing L7 (use a guard column)

Flow rate: 1 mL/min

Injection volume: 10 µL

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 1.5

Relative standard deviation: NMT 5.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of each impurity in the portion of Xylazine taken:

Result = (r_u /r_s ) × (C_s /C_u ) × (1/F) × 100

r_u = peak area of any individual impurity from the Sample solution that is not present in the chromatogram of the Diluent

r_s = peak area of xylazine from the Standard solution

C_s = concentration of USP Xylazine RS in the Standard solution (mg/mL)

C_u = concentration of Xylazine in the Sample solution (mg/mL)

F = relative response factor (see Table 3)

Acceptance criteria: See Table 3.

Table 3

5 SPECIFIC TESTS

Loss on Drying 〈731〉

Analysis: Dry under vacuum at 60° for 4 h.

Acceptance criteria: NMT 0.5%

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers. Store at 25°, excursions permitted between 15° and 30°.

Labeling: Where it is intended for veterinary use only, the label so states.

USP Reference Standards 〈11〉

USP Xylazine RS