FDA Approves Levothyroxine Sodium Tablets for Hypothyroidism and TSH Suppression

Levothyroxine sodium is L-thyroxine (T4), a synthetic thyroid hormone. It acts by replacing endogenous thyroid hormone in patients with hypothyroidism and by suppressing TSH secretion in patients with thyroid cancer.

Levothyroxine sodium tablets are indicated for: - Hypothyroidism: replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism. - Pituitary Thyrotropin (TSH) Suppression: as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer. Limitations of Use: Not indicated for suppression of benign thyroid nodules and nontoxic diffuse goiter in iodine-sufficient patients; not indicated for treatment of hypothyroidism during the recovery phase of subacute thyroiditis.

- Administer once daily, preferably on an empty stomach, one-half to one hour before breakfast. - Administer at least 4 hours before or after drugs that interfere with absorption. - Starting dose depends on age, body weight, cardiovascular status, and concomitant medications. Peak therapeutic effect may not be attained for 4-6 weeks. - For primary hypothyroidism in adults and adolescents (growth and puberty complete): average full replacement dose is approximately 1.6 mcg/kg/day. Adjust dose by 12.5-25 mcg increments every 4-6 weeks. For elderly or patients with cardiac disease, start with 12.5-25 mcg/day and increase every 6-8 weeks. For severe longstanding hypothyroidism, start with 12.5-25 mcg/day and adjust every 2-4 weeks. - For secondary or tertiary hypothyroidism: start at full replacement dose in healthy non-elderly; lower dose in elderly or those with underlying cardiac disease. - For pediatric patients unable to swallow tablets, crush tablet and suspend in a small amount of water; administer immediately. Do not store suspension. Avoid foods that decrease absorption (e.g., soybean-based infant formula).

Trial data not available in label.

Not reported in label.

Levothyroxine sodium tablets are a standard replacement therapy for hypothyroidism and an adjunct in TSH suppression for thyroid cancer. They are not recommended for benign thyroid nodules or nontoxic goiter in iodine-sufficient patients due to lack of benefit and risk of hyperthyroidism.