USP Revises Potency Spec for Levothyroxine Sodium Tablets

Rockville, MD (Aug. 29)-The United States Pharmacopeial Convention (USP) announced an interim revision to its monograph for levothyroxine sodium tablets, which will become official in USP 32-NF 27. The revision narrows the assay acceptance criteria from the current requirement of “not less than 90.0% and not more than 110.0% of the labeled amount of levothyroxine sodium” to “not less than 95.0% and not more than 105.0% of the labeled amount of levothyroxine sodium.” The revision is meant to “address concerns about variability in the stability profile of FDA-approved levothyroxine sodium products and the clinical consequences of variability in achieving target thyroid levels.”

In October 2007, FDA notified holders of approved new drug applications and abbreviated new drug applications for levothyroxine sodium drug products that it will require all approved levothyroxine sodium drug products to meet a 95.0-105.0% range of label claim throughout their label shelf lives.