Levothyroxine · Levothyroxine Sodium, Thyquidity

What is Levothyroxine?

Levothyroxine is a synthetic L-thyroxine (T4) that binds thyroid hormone receptors in the cell nucleus to activate gene transcription and protein synthesis. It is used as replacement therapy for hypothyroidism and as an adjunct to surgery and radioiodine therapy for TSH suppression in well-differentiated thyroid cancer.

Summary written with AI from the sources listed at the end of this page.

At a glance

Also known as

Levothyroxine Sodium, Thyquidity, Unithroid

Drug type

Small molecule

Targets

thyroid hormone receptor alpha (THRA), thyroid hormone receptor beta (THRB)

Mechanism

Agonist of thyroid hormone receptor alpha (THRA) and thyroid hormone receptor beta (THRB)

Pathways

gene transcription, protein synthesis, cellular metabolism, thermogenesis

Therapy area

Endocrine, Oncology

Developer

Stevens J

In trials of

IRWD

FDA status

Approved as Levothyroxine Sodium, Thyquidity, Unithroid (August 21, 2000), NDA021210 · FDA label

✅ FDA-approved uses

• Hypothyroidism (Levothyroxine Sodium)
• Pituitary Thyrotropin (TSH) Suppression in well-differentiated thyroid cancer (Levothyroxine Sodium)
• Hypothyroidism (Thyquidity)
• Pituitary Thyrotropin (TSH) Suppression in well-differentiated thyroid cancer (Thyquidity)
• Hypothyroidism (Unithroid)
• Pituitary Thyrotropin (TSH) Suppression in well-differentiated thyroid cancer (Unithroid)

From the indications section of the FDA label (version of Apr 7, 2026). Read the full label for the exact wording, limitations and safety information.

🧪 Clinical trials

Trials of the companies BioRadar tracks, from ClinicalTrials.gov, most advanced phase first.

Conditions studied

Healthy Volunteers

Sources

• FDA label (DailyMed)
• FDA label Levothyroxine Sodium (2026-04-07), indications
• FDA label Thyquidity (2025-07-03), indications
• FDA label Unithroid (2019-06-19), indications
• NCI Thesaurus
• ClinicalTrials.gov NCT03856970

Updated Oct 3, 2026.