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Comment & Response
June 6, 2022

Considerations for Generic-to-Generic Levothyroxine Switching

Author Affiliations
  • 1Clinical Investigation Center, Department of Pharmacology, AP-HP Sorbonne Université, Pitié-Salpêtrière University Hospital, Paris, France
  • 2INSERM, CIC-1901 and UMR-S 1166, Faculty of Medicine, Sorbonne University, Paris, France
JAMA Intern Med. 2022;182(8):886-887. doi:10.1001/jamainternmed.2022.1987

To the Editor In their recent comparative effectiveness research article, Brito et al1 compared thyrotropin (TSH) levels in patients prescribed generic levothyroxine products who continued taking the same generic product with those who switched among generic products. From an initial population of 15 829 patients in a large administrative database, mean TSH levels and the proportion of patients with markedly abnormal TSH levels 6 weeks to 12 months after the index date of initial TSH assessment did not significantly differ in 2780 propensity-matched pairs of switchers and nonswitchers. This is an important study using levothyroxine therapy to address the broader question of whether generic products are interchangeable.

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