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Xylazine Hydrochloride
C12H16N2S.HCl 256.80

4H-1,3-Thiazin-2-amine, N-(2,6-dimethylphenyl)-5,6-dihydro-, monohydrochloride.
5,6-Dihydro-2-(2,6-xylidino)-4H-1,3-thiazine hydrochloride [23076-35-9].
» Xylazine Hydrochloride contains not less than 98.0 percent and not more than 102.0 percent of C12H16N2S·HCl.
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.
B: Thin-Layer Chromatographic Identification Test 201
Test solution: 5 mg per mL, in methanol.
Developing solvent system: methanol and ammonium hydroxide (98.5:1.5).
Procedure— Separately apply 1 µL of the Test solution and the Standard solution. Allow the applications to dry with the aid of a stream of nitrogen, develop in a saturated chromatographic chamber, and dry the plate in a current of air: the size, intensity, and RF value of the principal spot obtained from the Test solution correspond to those of the principal spot obtained from the Standard solution.
Melting range 741: between 164 and 168.
pH 791: between 4.0 and 6.0, in a solution (1 in 100).
Loss on drying 731 Dry it at 105 for 4 hours: it loses not more than 1.0% of its weight.
Residue on ignition 281: not more than 0.1%.
Heavy metals, Method II 231: 20 µg per g.
Chromatographic purity— Examine the chromatogram obtained from the Assay preparation. Calculate the percentage of impurities in the Xylazine Hydrochloride taken by the formula:
100rs / (rU + rs),
in which rs is the sum of the areas of all the impurity peaks observed; and rU is the area of the xylazine peak: the sum of the impurity responses is not greater than 2.0%.
Residual solvents 467: meets the requirements.
(Official January 1, 2007)
Mobile phase— Dissolve 6.0 g of sodium 1-heptanesulfonate in 2500 mL of water, add 60 mL of glacial acetic acid, dilute with water to 3000 mL, and mix. Prepare a mixture of 2200 mL of this solution and 1800 mL of methanol, and pass through a filter having a 0.5-µm or finer porosity. Make adjustments if necessary (see System Suitability under Chromatography 621).
Standard preparation— Prepare a solution of USP Xylazine Hydrochloride RS in Mobile phase having a known concentration of about 1 mg per mL.
Assay preparation— Transfer about 25 mg of Xylazine Hydrochloride, accurately weighed, to a 25-mL volumetric flask, dissolve in and dilute with Mobile phase to volume, and mix.
Chromatographic system (see Chromatography 621)— The liquid chromatograph is equipped with a 254-nm detector, a 2-mm × 2-cm guard column that contains packing L1, and a 3.9-mm × 30-cm analytical column that contains packing L1 and is maintained at a constant temperature of about 40. The flow rate is about 2.5 mL per minute. Chromatograph the Standard preparation, and record the peak responses as directed for Procedure: the relative standard deviation for replicate injections is not more than 2.0%. [NOTE—After daily use, rinse the column with 100 mL of acetonitrile and with 100 mL of methanol, and store the column containing methanol.]
Procedure— Separately inject equal volumes (about 20 µL) of the Standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C12H16N2S.HCl in the portion of Xylazine Hydrochloride taken by the formula:
25C(rU / rS),
in which C is the concentration, in mg per mL, of USP Xylazine Hydrochloride RS in the Standard preparation; and rU and rS are the areas of the xylazine peak responses in the chromatograms obtained from the Assay preparation and the Standard preparation, respectively.
Auxiliary Information— Staff Liaison : Ian DeVeau, Ph.D., Associate Director
Expert Committee : (VET05) Veterinary Drugs 05
USP29–NF24 Page 2273
Pharmacopeial Forum : Volume No. 29(6) Page 2005
Phone Number : 1-301-816-8178