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FAQs: Notice of Intent to Revise for Magnesium Family of Monographs

USP provides answers to Frequently Asked Questions (FAQs) as a service to stakeholders and others who are seeking information regarding USP’s organization, standards, standards-setting process, and other activities. These are provided for informational purposes only, and should not be construed as an official interpretation of USP text, or be relied upon to demonstrate compliance with USP standards or requirements. USP does not endorse any specific brand or product. For questions not answered here, please contact Michael Chang, Principal Scientist (    

See Notice of Intent to Revise here.

  1. Why is USP proposing to revise the magnesium family of monographs?
    Several comments were received indicating that stakeholders were unable to perform the new analytical method and unable to meet the acceptance criteria in the revisions to the magnesium monographs that became official on June 1, 2021. Other stakeholders noted that the revised monograph that became official on June 1, 2021 included ion chromatography for which they were unable to find a contract laboratory to conduct the monograph procedures.

  2. What is the revision being proposed in the Notice of Intent to Revise?
    The Expert Committee is proposing to revert the monographs to the previous versions that were official prior to June 1, 2021. This would include removing Identification B test, and reverting from ion chromatography to titration. Additionally, for the Magnesium Carbonate, Magnesium Hydroxide, Magnesium Hydroxide Paste, and Magnesium Oxide monographs, the Limit of calcium test will revert from ion chromatography back to atomic absorption spectrometry.

  3. What is the official date of the Revision Bulletins (RB)? How should manufacturers test and report for materials produced from now until the RB becomes official?
    USP published a notice of intent to revise to solicit feedback on the revision proposal. In the absence of significant adverse comments, it is anticipated that the proposed revision will be published as a RB on November 19, 2021 pursuant to the Rules and Procedures of the Council of Experts. The RB is anticipated to be official on December 1, 2022, 1 year from the time of publication. USP allows early adoption of the RB as outlined in the USP General Notices 3.10. Applicability of Standards. Thus, users will be able to early adopt the reverted monographs (versions official prior to June 1, 2021) or to continue to use the currently official monographs (versions official prior to June 1, 2021) until December 1, 2022. On December 1, 2022, the reverted monographs (versions official prior to June 1, 2021) will become official. Manufacturers should work with their applicable regulatory bodies on requirements for testing and reporting.

  4. Will USP consider future revisions to these monographs that will include ion chromatography?
    USP will investigate the issues around the magnesium family of monographs, solicit public feedback, and pursue a long-term solution to revise these monographs.

  5. How can I submit comments on the proposed revisions?
    USP is seeking feedback on the proposed revision. Stakeholders are encouraged to submit comments to Michael Chang, Principal Scientist ( by Oct 1, 2021.

    Updated September 2, 2021