- On February 28, 2022, The Journal of the American Medical Association Internal Medicine published an FDA co-authored original investigation titled “Association Between Generic-to-Generic Levothyroxine Switching and Thyrotropin Levels Among US Adults.” This peer-reviewed study found that switching among generic levothyroxine products made by different manufacturers does not show a significant difference in the level of thyroid stimulating hormone present in patients.
- On September 30, 2020, The Journal of the American Medical Association Network Open published an FDA co-authored article titled Comparative Effectiveness of Generic vs Brand-Name Levothyroxine in Achieving Normal Thyrotropin Levels.” This article reports on a study that found that generic levothyroxine is as effective as its brand name counterparts for the initial treatment of mild thyroid dysfunction.
In 2007, the Food and Drug Administration (FDA) 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.
This action was part of the agency’s ongoing efforts to address concerns about the variability in the stability profile of FDA approved levothyroxine sodium products and is consistent with FDA’s previous regulatory actions intended to ensure that levothyroxine sodium drug products maintain their quality throughout their shelf lives.
- Real-world Evidence from a Narrow Therapeutic Index Product (Levothyroxine) Reflects the Therapeutic Equivalence of Generic Drug Products
- Comparative Effectiveness of Generic vs Brand-Name Levothyroxine in Achieving Normal Thyrotropin Levels
- FDA Acts to Ensure Thyroid Drugs Don't Lose Potency Before Expiration Date
- Table of Approved Levothyroxine Sodium Oral Formulations (Tablet or Capsule)
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