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  1. Postmarket Drug Safety Information for Patients and Providers

Levothyroxine Sodium Product Information

The Food and Drug Administration (FDA) has issued letters to all new drug application (NDA) and abbreviated new drug application (ANDA) holders requiring that they change the specifications for their products so that all levothyroxine sodium products approved for use in humans will meet a 95% to 105% potency specification throughout their labeled shelf-lives. 

In addition, FDA will work with the United States Pharmacopeia (USP) to revise the potency specification indicated in the USP monograph for levothyroxine sodium tablets.

This action is part of the agency’s ongoing efforts to address concerns about the variability in the stability profile of FDA approved levothyroxine sodium products and the clinical consequences of variability in achieving target thyroid levels in particularly vulnerable patients, such as those with thyroid cancer.  It is consistent with FDA’s previous regulatory actions intended to ensure that levothyroxine sodium drug products maintain their quality throughout their shelf lives.  Levothyroxine sodium products are used by over 13 million patients. 

Related Information

For the following resources, please see the FDA Archive

  • Questions and Answers on Levothyroxine Sodium Products
  • Sample Letter to NDA and ANDA Holders of Levothyroxine Sodium products
  • Levothyroxine letter to USP
  • Public Meeting for Levothyroxine Sodium Therapeutic Equivalence May 23, 2005, Washington, DC
  • 2006 Endocrinologic and Metabolic Drugs Advisory Committee
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