4H-1,3-Thiazin-2-amine, N-(2,6-dimethylphenyl)-5,6-dihydro-;
5,6-Dihydro-2-(2,6-xylidino)-4H-1,3-thiazine [7361-61-7]
BRIEFING
Xylazine. This proposal is based on the version of the monograph official as of May 1, 2020. On the basis of comments received, it is proposed to revise the Labeling section to indicate that it is for veterinary use only. Additionally, it is proposed to revise the monograph with the following changes:
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Replace the use of 197U in Identification B with the chromatographic retention time agreement as obtained in the Assay.
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In the Assay:
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Delete the filtration procedure of Solution A, as it is general good lab practice.
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In the System suitability section, change the requirement of tailing factor from "NMT 2.0" to "0.8–1.8" to align with Chromatography 〈621〉 and the %RSD from "NMT 2.0%" to "NMT 1.0%" to reflect the performance of modern analytical instruments.
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In both the Assay and Organic Impurities tests, add the column particle size and include the re-equilibration step in the gradient table of the Mobile phase.
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In the Organic Impurities test:
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Add the target concentration to the Sample solution for clarification.
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In the System suitability section, add a Note and Table 3 to present relative retention times as an aid in peak assignment, update the name of impurity "2,6-Dimethylphenyl isothiocyanate" to the current nomenclature of "2,6-Xylyl isothiocyanate", and include the corresponding chemical name in the table footnote.
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Revise Table 4 in the Acceptance criteria to list only the relative response factors, the limits for the specified impurities, any unspecified impurity, and total impurities; and update the name of impurity "2,6-Dimethylphenyl isothiocyanate" to the current nomenclature of "2,6-Xylyl isothiocyanate".
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Update the storage condition in the Packaging and Storage section for clarity.
Additionally, minor editorial changes have been made to update the monograph to current USP style.
The comment period for this revision ends on January 31, 2025. In the absence of any significant adverse comment, it is proposed to implement this revision via an Interim Revision Announcement with an official date of May 1, 2025.
(SM3: J. Li)
Case ID—SUB-171