WASHINGTON The Food and Drug Administration is strengthening the potency specifications for levothyroxine sodium to ensure the drug retains its potency over its entire shelf life.
The agency is increasing the specifications from a 90 to 110 percent potency range to a 95 to 105 percent range. The percent ranges were changed following concerns about the product by healthcare professionals and patients.
Data taken by the FDA showed that some of the levothyroxine products like blister packs degrade quicker than other package types. Also, some of the strengths have been shown to degrade more rapidly than others.
Manufacturers and marketers have two years to comply with the revised specification. Levothyroxine sodium products are used by over 13 million patients.