What are levothyroxine sodium drug products and what are they used for?
Levothyroxine sodium is the sodium salt of the levo isomer of the thyroid hormone thyroxine. Thyroid hormones affect protein, lipid, and carbohydrate metabolism, growth, and development. Orally administered levothyroxine sodium is used as replacement therapy in conditions characterized by diminished or absent thyroid function, such as cretinism, myxedema, nontoxic goiter, or hypothyroidism. Levothyroxine sodium may be used to suppress the secretion of thyrotropin in the management of simple nonendemic goiter, chronic lymphocytic thyroiditis, and thyroid cancer. 3. Why is FDA taking this action? FDA believes that narrowing the potency specifications will improve the quality of certain levothyroxine sodium products. This action will address concerns about variability in the stability profiles of FDA-approved levothyroxine sodium products and the clinical consequences of this variability in stabilizing particularly vulnerable patients, such as those with thyroid cancer. This action is con
