Levothyroxine generic names
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Levothyroxine Generic Names and Formulations
Levothyroxine is a synthetic form of the thyroid hormone thyroxine (T4) and is widely used to treat hypothyroidism. It is available under several brand names and as multiple generic formulations. The most well-known brand names include Synthroid and Levoxyl (previously called Levoxine) 13. Generic versions are typically labeled as "levothyroxine sodium" and are produced by various manufacturers 24.
Common Generic Levothyroxine Names
The generic name for this medication is "levothyroxine sodium." In the United States, several generic manufacturers produce levothyroxine sodium tablets, which are considered interchangeable with brand-name products if they meet the Food and Drug Administration (FDA) bioequivalence criteria 1234. Some of the generic manufacturers include Sandoz, Mylan, and others, but the product is always labeled as "levothyroxine sodium" regardless of the manufacturer 26.
Brand vs. Generic Levothyroxine: Bioequivalence and Interchangeability
Studies have shown that both brand-name and generic levothyroxine sodium products are generally bioequivalent, meaning they deliver similar amounts of the active hormone into the bloodstream 138. The FDA requires that generic versions fall within a specific range (80-125%) of the brand-name product’s absorption and concentration in the body 18. This has led to the approval of multiple generic versions, which are often substituted at the pharmacy level 24.
Clinical Considerations When Switching Between Generic Levothyroxine Products
While most patients can safely switch between generic and brand-name levothyroxine sodium, some studies and clinical guidelines suggest caution, especially in vulnerable populations such as children with severe congenital hypothyroidism, the elderly, pregnant women, and those requiring precise thyroid hormone dosing 26. In these cases, even small differences between formulations may affect thyroid-stimulating hormone (TSH) levels and overall thyroid function 26.
Recent large studies have found that switching between different generic manufacturers of levothyroxine sodium does not usually result in significant changes in TSH levels for most adults, challenging previous concerns about switching between generics 79. However, some evidence suggests that persistent use of a single brand-name product like Synthroid may be associated with slightly better TSH control compared to generics, though the difference is small .
Conclusion
The generic name for levothyroxine is "levothyroxine sodium," and it is available from multiple manufacturers. Most patients can use generic versions interchangeably with brand-name products, but special populations may require closer monitoring. If a switch between products occurs, it is recommended to check TSH levels and adjust the dose if necessary to ensure optimal thyroid function 26.
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