Levothyroxine sodium

Catalog No.S3747 Synonyms: L-T4 sodium, L-Thyroxine sodium, LT4 sodium

For research use only.

Levothyroxine (L-T4, L-Thyroxine) is the major hormone derived from the thyroid gland. It is the agonist of Thyroid hormone receptor alpha and beta.

Levothyroxine sodium Chemical Structure

CAS No. 55-03-8

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Biological Activity

Description Levothyroxine (L-T4, L-Thyroxine) is the major hormone derived from the thyroid gland. It is the agonist of Thyroid hormone receptor alpha and beta.
In vitro

Levothyroxine can upregulate the expression of P-gp mRNA and protein in LS180 cells and can produce the same effect in Caco-2 cells, which are relatively lacking in PXR. It doea not affect the expression of CYP3A4 in either cell line[1].

In vivo Levothyroxine is a synthetic T4 hormone that is biochemically and physiologically indistinguishable from the natural one, and it is administered when the body is deficient in the natural hormone. Its nain site of absorption is small intestine, more specifically through the duodenum, jejunum and ileum. Very little is absorbed in the stomach. The bioavailability is about 70-80 % in euthyroid person and may be slightly higher in hyperthyroid patients. The absorption of levothyroxine appears to be influenced by gastric pH. Tmax=2-3 hours and the half-time T1/2 is 6.2 and 7.5 days in euthyroid and hypothyroid patients, respectively[3]. T4 hormones is known to modulate the expression of ionic channels, pumps and regulatory contractile proteins. T4-treatment induces a dose-dependent increase in the duration of contractions. Abnormal uterine contractile pattern are induced by T4-treatment[2].

Protocol (from reference)

Cell Research:[1]
  • Cell lines: LS180V cells
  • Concentrations: 100 nM and 100 μM
  • Incubation Time: 72 h
  • Method: LS180V cells are induced for 72 h with two different concentrations of l-T4: 100 nM and 100 μM.
Animal Research:[2]
  • Animal Models: Sprague-Dawley rats
  • Dosages: 20 μg/kg/day and 100 μg/kg/day
  • Administration: i.p.

Solubility (25°C)

In vitro

Chemical Information

Molecular Weight 798.85


CAS No. 55-03-8
Storage 3 years -20°C powder
2 years -80°C in solvent
Smiles C1=C(C=C(C(=C1I)OC2=CC(=C(C(=C2)I)O)I)I)CC(C(=O)[O-])N.[Na+]

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Clinical Trial Information

NCT Number Recruitment Interventions Conditions Sponsor/Collaborators Start Date Phases
NCT04037748 Completed Drug: Puran T4®|Drug: Eutirox® Healthy Merck Healthcare KGaA Darmstadt Germany an affiliate of Merck KGaA Darmstadt Germany June 25 2019 Phase 1

(data from https://clinicaltrials.gov, updated on 2022-08-01)

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