Liothyronine Sodium

What it is and how it works

Mechanism of Action Thyroid hormones exert their physiologic actions through control of DNA transcription and protein synthesis. Triiodothyronine (T3) and L-thyroxine (T4) diffuse into the cell nucleus and bind to thyroid receptor proteins attached to DNA. This hormone nuclear receptor complex activates gene transcription and synthesis of messenger RNA and cytoplasmic proteins. The physiological actions of thyroid hormones are produced predominantly by T3, the majority of which (approximately 80%) is derived from T4 by deiodination in peripheral tissues.

Indications

Liothyronine sodium is an L-triiodothyronine (T3) indicated for: Hypothyroidism: As replacement in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism Pituitary Thyrotropin (Thyroid-Stimulating Hormone, TSH) Suppression: As an adjunct to surgery and radioiodine therapy in the management of well-differentiated thyroid cancer Thyroid Suppression Test: As a diagnostic agent in suppression tests to differentiate suspected mild hyperthyroidism or thyroid gland autonomy 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. Hypothyroidism Liothyronine Sodium Tablets, USP are indicated as a replacement therapy in primary (thyroidal), secondary (pituitary), and tertiary (hypothalamic) congenital or acquired hypothyroidism.

Dosage and administration (summary)

Administer Liothyronine Sodium Tablets, USP orally once daily and individual dosage according to patient response and laboratory findings See full prescribing information for recommended dosage for hypothyroidism TSH suppression in well-differentiated thyroid cancer and for thyroid suppression test When switching a patient to Liothyronine Sodium Tablets, USP discontinue levothyroxine therapy and initiate Liothyronine Sodium Tablets, USP at a low dosage.

Contraindications

Liothyronine Sodium Tablets, USP are contraindicated in patients with uncorrected adrenal insufficiency . Uncorrected adrenal cortical insufficiency

Warnings and precautions

Cardiac adverse reactions in the elderly and in patients with underlying cardiovascular disease: Initiate Liothyronine Sodium Tablets, USP at less than the full replacement dose because of the increased risk of cardiac adverse reactions, including atrial fibrillation ( 2.3 , 5.1 , 8.5 ) Myxedema coma: Do not use oral thyroid hormone drug products to treat myxedema coma.

Pregnancy

Pregnancy Risk Summary Experience with liothyronine use in pregnant women, including data from post-marketing studies, have not reported increased rates of major birth defects or miscarriages (see Data ). There are risks to the mother and fetus associated with untreated hypothyroidism in pregnancy.

Storage and supply

Store between 15°C and 30°C (59°F and 86°F).

Source: Liothyronine Sodium (Liothyronine Sodium) — US FDA prescribing information, 2024-02-12, DailyMed. Summarised and shortened; the full label governs. Iranian registration, indications and labelling may differ.