BRIEFING

 Dimethyl Isosorbide. This proposal is based on the version of the monograph to be official on May 1, 2025. On the basis of comments and lab work received, it is proposed to make the following changes:

1. Revise Identification B by replacing the Refractive Index identification test with a test for Chromatographic Identity based on the retention time agreement as obtained in the Assay.

2. Update Carrier gas information and add a Run time in the Assay.

3. Update the test for Organic Impurities with the USP RS for impurities, calculations, and Acceptance criteria. The acceptance criteria is updated with the identified impurities such as dimethyl isomannide, dimethyl isoidide, and monomethyl isosorbide.

4. Under the test for Organic Impurities, replace the Standard solution with Standard solution A and add System suitability solution and Standard solution B. Additionally, add resolution criteria between dimethyl isosorbide and dimethyl isomannide peaks under Suitability requirements.

5. Add USP Dimethyl Isoidide RS and USP Dimethyl Isomannide RS to the USP Reference Standards section.

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

 (SE: S. Saladi)

 Case ID—SUB-169