FDA to Monitor Thyroid Drug For Potency, Expiration Date

Concerns have been expressed about a drug called levothyroxine sodium, which is used to treat underactive thyroid glands as well as other conditions of the thyroid. The concern is that the drug may lose its potency before the expiration date. Because of this, the U.S. Food and Drug Administration is tightening the specifications regarding the potency of the drug.

This decision will affect a large part of the population because it is being used by more than 13 million patients.

The FDA is mandating that the products tighten up their potency specifications to meet a 95% to 105% potency level until their expiration dare. The lower 95% potency specification will insure that the drugs do not lose more than 5% of their potency level and the higher 105% level is to allow for any testing variability. As it stands now, these products are allowed a potency range of 90 to 100%.

The actions have been taken on the advice of a joint FDA advisory committee and it reflects concerns raised about the products from both health care professionals and patients.

The manufacturers and marketers have up to two years to comply with the revised specification.

The data that the decision was based on showed that the products were showing a trend toward to losing their potency, with some of them showing a potency of 90% of whatever the potency was stated to be by the expiration date.

Even though all of the approved products do fall within the current guidelines, the data showed that some products rapidly degrade over their labeled shelf life. Some strengths
and some and different package types like blister packs, degrade faster than others and that results in varying expiration dates within the lines. Also, there is variability in expiration dating periods with products from different manufacturers. Some of the products remain very stable and lose less than 5% of the stated potency within 24 months. On the other end of the spectrum, there are some products that lost 10% of their potency in 9 months.

By tightening the potency specification and limiting the amount that products can degrade over their shelf life, the FDA states that they will be able to reduce the variability between the different products and thus it will have an impact for achieving the target thyroid levels, especially for the most vulnerable patients such as those with thyroid cancer.

The agency also recommends that customers keep their medications in a dry place at room temperature and to avoid humid, hot places like bathrooms. Storing your medications right can help to preserve their potency.

Source; FDA http://www.fda.gov/bb