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 98.0percent and not more than 102.0percent of C12H16N2S·HCl.
Packaging and storage— Preserve in tight containers.Store at 25,excursions permitted between 15and 30.
Labeling— Where it is intended for veterinary use only,the label so states.
Identification—
A:Infrared Absorption á197Kñ.
B:Thin-Layer Chromatographic Identification Test á201ñ—
Test solution: 5mg per mL,in methanol.
Developing solvent system: methanol and ammonium hydroxide (98.5:1.5).
Procedure— Separately apply 1µLof the Test solutionand 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 RFvalue of the principal spot obtained from the Test solutioncorrespond to those of the principal spot obtained from the Standard solution.
Melting range á741ñ: between 164and 168.
pHá791ñ: between 4.0and 6.0,in a solution (1in 100).
Loss on drying á731ñ— Dry it at 105for 4hours:it loses not more than 1.0%of its weight.
Residue on ignition á281ñ: not more than 0.1%.
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 rsis the sum of the areas of all the impurity peaks observed;and rUis the area of the xylazine peak:the sum of the impurity responses is not greater than 2.0%.
Assay—
Mobile phase— Dissolve 6.0g of sodium 1-heptanesulfonate in 2500mLof water,add 60mLof glacial acetic acid,dilute with water to 3000mL,and mix.Prepare a mixture of 2200mLof this solution and 1800mLof methanol,and pass through a filter having a 0.5-µm or finer porosity.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).
Standard preparation— Prepare a solution of USP Xylazine Hydrochloride RSin Mobile phasehaving a known concentration of about 1mg per mL.
Assay preparation— Transfer about 25mg of Xylazine Hydrochloride,accurately weighed,to a 25-mLvolumetric flask,dissolve in and dilute with Mobile phaseto volume,and mix.
Chromatographic system(see Chromatography á621ñ)— 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 L1and is maintained at a constant temperature of about 40.The flow rate is about 2.5mLper 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 100mLof acetonitrile and with 100mLof methanol,and store the column containing methanol.]
Procedure— Separately inject equal volumes (about 20µL)of the Standard preparationand the Assay preparationinto 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 Cis the concentration,in mg per mL,of USP Xylazine Hydrochloride RSin the Standard preparation;and rUand rSare the areas of the xylazine peak responses in the chromatograms obtained from the Assay preparationand the Standard preparation,respectively.
Auxiliary Information— Staff Liaison:Ian DeVeau,Ph.D.,Senior Scientist
Expert Committee:(VET)Veterinary Drugs
USP28–NF23Page 2040
Pharmacopeial Forum:Volume No.29(6)Page 2005
Phone Number:1-301-816-8178
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