In accordance with the Rules and Procedures of the 2010–2015 Council of Experts, the Monographs—Small Molecules 3 Expert Committee has revised the Levothyroxine Sodium monograph.
The purpose for the revision is to add a new specified impurity, levothyroxine N–methylamide, with a limit of NMT 0.15% to the Impurity Table 2 under Organic Impurities, Procedure 2. As the result of recent improvement of separation efficiency of YMC columns, this previously undetected impurity now appears separated from the main peak, eluting at the relative retention time of 0.97. The limit of total impurities remains unchanged.
The Levothyroxine Sodium Monograph Revision Bulletin supersedes the currently official monograph. The Revision Bulletin will be incorporated in the First Supplement to USP 34–NF 29.
Should you have any questions, please contact Elena Gonikberg, Ph.D. (301-816-8251 or EG@usp.org).