Packaging and storage— Preserve in well-closed disposable syringes.

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

USP Reference standards á11ñ— USP Amoxicillin RS.

Identification— Transfer a quantity of Intramammary Infusion,equivalent to about 60mg of amoxicillin,to a 50-mLcentrifuge tube,add 25mLof toluene,mix,and centrifuge.Decant and discard the toluene.Wash the residue with four 25-mLportions of toluene,sonicating for about 30seconds after each addition of toluene.Dry the residue in vacuum over silica gel.Add 15mLof 0.1Nhydrochloric acid to the residue,and mix.The solution obtained responds to the Identificationtest under Amoxicillin Capsules.

Water,Method Iá921ñ: not more than 1.0%,20mLof a mixture of toluene and methanol (7:3)being used in place of methanol in the titration vessel.

Assay— Proceed as directed for amoxicillin under Antibiotics—Microbial Assays á81ñ.Expel the contents of 1syringe of Intramammary Infusion into a high-speed glass blender jar containing 499.0mLof Buffer No.3and 1.0mLof polysorbate 80,and blend for 3to 5minutes.Allow to stand for about 10minutes,and dilute an accurately measured volume of the aqueous phase quantitatively and stepwise with Buffer No.3to obtain a Test Dilutionhaving a concentration assumed to be equal to the median dose level of the Standard.

Expert Committee:(VET)Veterinary Drugs

USP28–NF23Page 144

Phone Number:1-301-816-8178