Tylosin Granulated »Tylosin Granulated contains tylosin phosphate mixed with suitable carriers and inactive ingredients.It contains not less than 80.0percent and not more than 120.0percent of the labeled amount of tylosin. Packaging and storage— Preserve in well-closed,polyethylene-lined or polypropylene-lined containers,protected from moisture and excessive heat. Labeling— Label it to indicate that it is for animal use only.Label it also to indicate that it is for manufacturing,processing,or repackaging. USP Reference standards á11ñ USP Tylosin RS. Identification— A: The chromatogram of the Test solution,obtained as directed in the test for Content of tylosins,exhibits a major peak for tylosin A,the retention time of which corresponds to that exhibited in the chromatogram of the Standard solutionobtained as directed in the test for Content of tylosins. B: Transfer 2g of Tylosin Granulated to a test tube,add 10mLof water,and shake for 5minutes.Filter the resulting suspension,and if necessary adjust the pHof the filtrate to a pHbetween 6and 8with 0.1Nsodium hydroxide or 0.1Nhydrochloric acid.This solution responds to the tests for Phosphate á191ñ. Loss on drying á731ñ Dry about 1g of it,accurately weighed,in vacuum at a pressure of not more than 5mm of mercury at 60for 5hours:it loses not more than 12.0%of its weight. Powder fineness á811ñ: not less than 99%passes a No.20sieve,and not more than 10%passes a No.80sieve. Content of tylosins— Mobile phase ,Standard solution,and Chromatographic system—Proceed as directed in the test for Content of tylosinsunder Tylosin. pH7.0buffer— Dissolve 13.6g of monobasic potassium phosphate in 1000mLof water,and adjust with 12Nsodium hydroxide to a pHof 7.0. Test solution— Transfer about 1.4g of Tylosin Granulated,accurately weighed,to a 250-mLvolumetric flask,add 100mLof pH7.0buffer,and shake by mechanical means for about 30minutes.Dilute with water to volume,mix,and filter.Transfer 10.0mLof the filtrate to a 50-mLvolumetric flask,dilute with water to volume,and mix.Filter a portion of this solution through a filter having a porosity of 0.5µm or finer,and use the filtrate as the Test solution. Procedure— Separately inject equal volumes (about 20µL)of the Standard solutionsand the Test solutioninto the chromatograph,record the chromatograms over a period of time that is about twice the elution time of the main tylosin Apeak,and measure the areas for all the major peaks:the relative retention times are about 0.5for tylosin C,0.7for tylosin B,0.9for tylosin D,and 1.0for tylosin A.Calculate the percentages of tylosin A,tylosin B,tylosin C,and tylosin Din the Tylosin taken by the formula: 100(ri/rs), in which riis the area of the tylosin Apeak,tylosin Bpeak,tylosin Cpeak,or tylosin Dpeak,as appropriate,in the chromatogram obtained from the Test solution,and rsis the sum of the areas of all of the peaks in the chromatogram obtained from the Test solution:the content of tylosin Ais not less than 80%,and the sum of the contents of tylosin A,tylosin B,tylosin C,and tylosin Dis not less than 95%. Assay— Proceed as directed for Tylosin under Antibiotics—Microbial Assays á81ñ.Prepare the Test Dilutionas follows.Transfer about 2g of Tylosin Granulated,accurately weighed,to a suitable container,add 200.0mLof a mixture of Buffer No.3and methanol (1:1),seal to prevent evaporation,and shake by mechanical means for about 60minutes.Filter the suspension so obtained,discarding the first 5mLof the filtrate.Dilute an accurately measured portion of the filtrate quantitatively and stepwise with a mixture of Buffer No.3and methanol (1:1)to obtain a Test Dilutionhaving an estimated concentration of about 4µg of tylosin per mL. Auxiliary Information— Staff Liaison:Ian DeVeau,Ph.D.,Senior Scientist Expert Committee:(VET)Veterinary Drugs USP28–NF23Page 2002 Phone Number:1-301-816-8178