BRIEFING

 Clioquinol. This proposal is based on the version of the monograph official as of May 1, 2020. It is proposed to make the following changes:

1. Add a third chemical name, 5-Chloro-7-iodoquinolin-8-ol, to the Chemical Information section.

2. Delete the sample drying conditions and add a "calculated on the dried basis" statement in the Definition to be consistent with current USP style.

3. Identification A is replaced with a reference to Spectroscopic Identification Tests 〈197〉 using either 197A or 197K.

4. Identification B is replaced with the retention time agreement of the major peak of the Sample solution and the Standard solution, as proposed in the updated HPLC Assay.

5. Identification C is deleted, as Identification A and Identification B can adequately establish the identity of clioquinol.

6. The gas chromatographic Assay procedure is replaced with a stability-indicating liquid chromatographic procedure based on the Clioquinol monograph from European Pharmacopoeia 10.5.

7. Add a validated HPLC test procedure for Organic Impurities and the Acceptance criteria for impurities based on the Clioquinol monograph from European Pharmacopoeia 10.5.

8. The liquid chromatographic procedure in the Assay and the Organic Impurities test is based on validation performed with the Zorbax Eclipse Plus-C8 brand of column with L7 packing. The typical retention time for clioquinol is about 16 min.

9. Add USP Clioquinol Related Compound A RS, USP Clioquinol Related Compound B RS, and USP Iodoquinol RS to the USP Reference Standards section in support of the proposed Organic Impurities test.

 Manufacturers are encouraged to submit their specifications to USP if they are different from those proposed in this revision.

 Additionally, minor editorial changes have been made to update the monograph to current USP style.

 (SM1: S. Ramakrishna)

 Correspondence Number—C251555