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# CDER Sees Generic Equality in a Levothyroxine Study
- URL: https://www.fdaweb.com/cder-sees-generic-equality-in-a-levothyroxine-study/
- Published: 2020-10-05T12:00:00.000Z
- Updated: 2026-09-14T16:31:19.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5147803

A new CDER investigation of real-world evidence confirms that patients taking levothyroxine benefit equally from generic and brand-name drugs. The study, the agency says, confirms that real-world equivalence, just like clinical trial data, shows that generic drugs are therapeutically equivalent to brand-name drugs.

The [review ](https://www.fda.gov/drugs/news-events-human-drugs/real-world-evidence-narrow-therapeutic-index-product-levothyroxine-reflects-therapeutic-equivalence?utm%5Fmedium=email&utm%5Fsource=govdelivery)by CDER scientists, in collaboration with academic experts, used a national administrative claims database to identify patients who first started levothyroxine between 2008 and 2017\. The study examined the effect of generic versus brand-name levothyroxine use in the clinical management of thyroid status. CDER says the review found “similar attainment of normal thyroid status following levothyroxine treatment for patients with mild or subclinical hypothyroidism, regardless of whether generic or brand-name medicine had been administered.”

The review did note that the “rate at which generic levothyroxine is prescribed lags the rate at which other generic drugs are prescribed. This lag may reflect the hesitancy of some prescribers to prescribe generic levothyroxine, but the real-world evidence provided from the study described here should assure clinicians and patients that generic levothyroxine is as effective as brand-name levothyroxine as initial therapy for hypothyroidism. CDER scientists are committed to generating real-world evidence for the use of generics, particularly for narrow therapeutic index products, and continue to pursue studies that examine clinical outcomes and the effects of switching between brand-name and generic levothyroxine for the treatment of hypothyroidism.”