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levothyroxine

Trade name: Synthroid

Small moleculeapproved

Approved

Apr 14, 1967

Levothyroxine (T4) is a synthetically prepared levo isomer of thyroxine, the major hormone secreted from the thyroid gland. Thyroxine is released from thyroglobulin by proteolysis and secreted into the blood. Thyroxine is peripherally deiodinated to form triiodothyronine (T3) which exerts a broad spectrum of stimulatory effects on cell metabolism. Thyroid hormone increases the metabolic rate of cells of all tissues in the body. In the fetus and newborn, thyroid hormone is important for the growth and development of all tissues including bones and the brain. In adults, thyroid hormone helps to maintain brain function, food metabolism, and body temperature, among other effects. The symptoms of thyroid deficiency relieved by levothyroxine include slow speech, lack of energy, weight gain, hair loss, dry thick skin and unusual sensitivity to cold. Levothyroxine acts like the endogenous thyroid hormone thyroxine (T4, a tetra-iodinated tyrosine derivative). In the liver and kidney, T4 is converted to T3, the active metabolite. In order to increase solubility, the thyroid hormones attach to thyroid hormone binding proteins, thyroxin-binding globulin, and thyroxin-binding prealbumin (transthyretin). Transport and binding to thyroid hormone receptors in the cytoplasm and nucleus then takes place. Thus by acting as a replacement for natural thyroxine, symptoms of thyroxine deficiency are relieved. Levothyroxine is used for use alone or in combination with antithyroid agents to treat hypothyroidism, goiter, chronic lymphocytic thyroiditis, myxedema coma, and stupor. — NCATS

Clinical trial activity

133 trials · 163 clinical orgs · 41 marketing orgs

Phase 1
26
Phase 2
32
Phase 3
23
Phase 4
41

Earliest trial started Jan 1, 2003 (NCT00648557)

Timeline

1950s

  1. Apr 14, 1955

    Knoll — First NDA Organization

  2. Apr 14, 1955

    Knoll — NDA Organization

1960s

  1. Apr 14, 1967

    Earliest FDA Approval

  2. Nov 21, 1969

    Allergan — NDA Secondary Org

2000s

  1. Aug 21, 2000

    Jerome Stevens Pharmaceuticals — Marketing Organization

  2. Aug 21, 2000

    Jerome Stevens Pharmaceuticals — NDA Secondary Org

  3. May 25, 2001

    King Pharmaceuticals — NDA Secondary Org

  4. Mar 1, 2002

    Cediprof Inc — NDA Secondary Org

  5. May 31, 2002

    Provell — NDA Secondary Org

  6. May 31, 2002

    Merck Serono — Marketing Organization

  7. Jun 5, 2002

    Mylan — Marketing Organization

  8. Jul 24, 2002

    AbbVie — NDA Secondary Org

  9. Oct 24, 2002

    Lloyd — NDA Secondary Org

  10. Oct 24, 2002

    Alvogen — NDA Secondary Org

  11. Jan 1, 2003

    Mylan — Earliest Phase 1 Sponsor(trial)

  12. Jun 6, 2003

    Genus Oncology, LLC — NDA Secondary Org

  13. Jan 1, 2004

    Earliest Phase 2 Sponsor(trial)

  14. Jun 16, 2005

    Merck KGaA — Marketing Organization

  15. Jan 1, 2006

    Earliest Phase 3 Sponsor(trial)

  16. Oct 13, 2006

    IBSA Institut Biochimique SA — NDA Secondary Org

  17. Oct 13, 2006

    IBSA Institut Biochimique SA — Marketing Organization

2010s

  1. Jun 24, 2011

    Fresenius — NDA Secondary Org

  2. Dec 7, 2015

    Par Pharmaceuticals — Marketing Organization

  3. Dec 7, 2015

    Bristol-Myers Squibb — Marketing Organization

  4. Dec 7, 2015

    PH HEALTH — Marketing Organization

  5. Jun 29, 2016

    Piramal — Marketing Organization

  6. Dec 21, 2018

    Maia Pharms Inc — Marketing Organization

  7. Jan 18, 2019

    Lupin — Marketing Organization

  8. Feb 19, 2019

    Amneal Pharmaceuticals — Marketing Organization

2020s

  1. Mar 27, 2020

    Dr. Reddy's Laboratories — Marketing Organization

  2. Oct 19, 2020

    Accord Research — Marketing Organization

  3. Oct 28, 2020

    Teva — Marketing Organization

  4. Oct 28, 2020

    Ani Pharmaceuticals — Marketing Organization

  5. Nov 30, 2020

    Reguliance Llc — Marketing Organization

  6. Nov 30, 2020

    Azurity — Marketing Organization

  7. Nov 30, 2020

    Empi — Marketing Organization

  8. Nov 30, 2020

    VistaPharm, Inc. — Marketing Organization

  9. Nov 30, 2020

    Azurity — NDA Secondary Org

  10. May 17, 2021

    Hikma — Marketing Organization

  11. May 17, 2021

    Custopharm Inc — Marketing Organization

  12. May 17, 2021

    Hikma — NDA Secondary Org

  13. Apr 29, 2022

    Mylan — NDA Secondary Org

  14. Nov 25, 2022

    Zydus Discovery DMCC — Marketing Organization

  15. Dec 21, 2022

    Macleods Pharmaceuticals, Ltd — Marketing Organization

  16. Dec 21, 2022

    Neogen — Marketing Organization

  17. Jan 18, 2023

    Ascent Pharmahealth — Marketing Organization

  18. Jan 18, 2023

    AbbVie — Marketing Organization

  19. Jul 16, 2024

    Aurobindo Pharma — Marketing Organization

  20. Nov 29, 2024

    Exeltis — Marketing Organization

  21. Mar 5, 2025

    ONESOURCE SPECIALTY — Marketing Organization

  22. May 20, 2026

    Alembic — Marketing Organization

Indications

Approved for

Studied for

Mechanism of action

Combination products

Approval history

  • approvedApr 14, 1967

Chemistry & pharmacology

Loading structure…

SMILES

N[C@@H](CC1=CC(I)=C(OC2=CC(I)=C(O)C(I)=C2)C(I)=C1)C(O)=O
Mol. weight
776.87 g/mol
Lipinski Ro5
1 violation(s)
Rule of 3
No
Chirality
Single Stereoisomer
Inorganic
No
Polymer
No
Delivery
Oral, Parenteral
Availability
Prescription Only

Oral

Yes

Parenteral

Yes

Topical

No

Black box warning

Sources

Also known as

  • 3,3',5,5'-tetraiodo-l-thyronine
  • 3,3',5,5'-tetraiodo-l-thyronine
  • 3,5,3',5'-tetraiodo-l-thyronine
  • 3,5,3',5'-tetraiodo-l-thyronine
  • 4-(4-hydroxy-3,5-diiodophenoxy)-3,5-diiodo-l-phenylalanine
  • 4-(4-hydroxy-3,5-diiodophenoxy)-3,5-diiodo-l-phenylalanine
  • choloxin
  • choloxin
  • choloxin
  • choloxin
  • dt4
  • eltroxin
  • eltroxin
  • eltroxin
  • euthroid
  • euthroid
  • euthroid
  • euthyral
  • evotrox
  • levolet
  • levolet
  • levo-t
  • levo-t
  • levothroid
  • levothroid
  • levothroid
  • levothyroid
  • levothyroid
  • levothyroxin
  • levothyroxin
  • levothyroxine
  • levothyroxine
  • levothyroxine
  • levothyroxine
  • levothyroxine
  • levothyroxine
  • levothyroxine
  • levothyroxine
  • levothyroxine
  • levothyroxine sodium
  • levothyroxine sodium
  • levothyroxine sodium
  • levothyroxine sodium
  • levothyroxine sodium
  • levothyroxine sodium anhydrous
  • levothyroxine sodium anhydrous
  • levothyroxine sodium anhydrous
  • levothyroxine sodium anhydrous
  • levothyroxine sodium anhydrous
  • levothyroxine sodium anhydrous
  • levothyroxine sodium hydrate
  • levothyroxine sodium - liothyronine sodium mixt
  • levothyroxine sodium - liothyronine sodium mixt
  • levothyroxine sodium pentahydrate
  • levothyroxin natrium
  • levoxine
  • levoxine
  • levoxyl
  • levoxyl
  • liotrix
  • liotrix
  • liotrix
  • liotrix
  • liotrix (t4;t3)
  • liotrix (t4;t3)
  • liotrix (t4;t3)
  • lt4
  • lt4
  • l-t4
  • l-t4
  • l-thryoxine
  • l-thyroxine
  • l-thyroxine
  • l-thyroxine
  • l-thyroxine
  • l-thyroxine henning
  • novothyrox
  • novothyrox
  • o-(4-hydroxy-3,5-diidophenyl)-3,5-diiodo-l-tyrosine
  • o-(4-hydroxy-3,5-diidophenyl)-3,5-diiodo-l-tyrosine
  • o-(4-hydroxy-3,5-diiodophenyl)-3,5-diiodo-d-tyrosine
  • o-(4-hydroxy-3,5-diiodophenyl)-3,5-diiodo-d-tyrosine
  • o-(4-hydroxy-3,5-diiodophenyl)-3,5-diiodo-l-tyrosine
  • o-(4-hydroxy-3,5-diiodophenyl)-3,5-diiodo-l-tyrosine
  • o-(4-hydroxy-3,5-diiodophenyl)-3,5-diiodo-l-tyrosine mixt. with o-(4-hydroxy-3-iodophenyl)-3,5-diiodo-l-tyrosine
  • sodium l-triiodothyronine
  • sodium l-triiodothyronine
  • soloxine
  • soloxine
  • synthroid
  • synthroid
  • synthroid
  • t4
  • t4
  • t4
  • t4
  • tetraiodothyronine
  • thryoid hormone
  • thryoxine
  • thyreotom
  • thyrolar
  • thyrol l
  • thyroxine
  • thyroxine sodium
  • thyroxine - triiodothyronine combination
  • thyroxine - triiodothyronine combination, monosodium salt
  • thyroxine, triiodothyronine drug combination
  • thyroxin sodium
  • tirosint
  • tirosint
  • triiodothyronine - thyroxine combination
  • unithroid
  • unithroid

Clinical trials

NCT IDPhaseStart dateSponsor(s)
NCT06790589Phase 2Dec 31, 2025University of Alberta, University of Calgary
NCT07239674Phase 3Nov 30, 2025Air Force Military Medical University, China, Chongqing Medical University, Guizhou Medical University, Hacettepe University, Inner Mongolia Medical University, Kunming Medical University, Ningxia Medical University, Qingdao University, Shanxi Medical University, Sichuan University, Sun Yat-Sen University, Xiamen University, Zhejiang University
NCT07011953Early Phase 1 (Phase 1)Jul 1, 2025Peking University
NCT06971965N/AJun 2, 2025National Cancer Center, Korea, Seoul National University, The National Cancer Center
NCT06999278Phase 3Jun 1, 2025Zhejiang University
NCT06731764Phase 2/Phase 3 (Phase 3)Dec 10, 2024University of Connecticut
NCT06652113N/ADec 1, 2024Sun Yat-Sen University
NCT06660823Phase 3Nov 30, 2024Ain Shams University
NCT06653907Phase 4Oct 25, 2024Fourth Hospital of Shijiazhuang City, Government of China, Peking University
NCT06373523Early Phase 1 (Phase 1)Sep 1, 2024Postgraduate Institute of Medical Education and Research
NCT06625814Phase 1Jul 8, 2024Celerion, Merck
NCT06345339Phase 2/Phase 3 (Phase 3)Apr 26, 2024AbbVie
NCT06428097Phase 1Mar 29, 2024University of California, San Francisco
NCT06276205Phase 3Mar 1, 2024King Edward Medical University
NCT06073665Phase 4Nov 15, 2023National Institute on Aging (NIA), University of Pennsylvania
NCT05823012Phase 2Apr 21, 2023Xeris Pharmaceuticals
NCT05712421Phase 2Feb 28, 2023Neuvosyn Laboratories, LLC
NCT05526144Phase 2Jan 1, 2023Department of Veteran Affairs, Truman Medical Center
NCT05240911N/AJun 1, 2022Zhejiang University
NCT05412979Phase 2Apr 29, 2022Sention Therapeutics, LLC
Showing 20 of 133 trials
Page 1 / 7

Organizations

Research & Development (163)

OrganizationOrg typeTrialsAs lead sponsorPhasesEarliest year
University of BernAcademic/Hospital7612013
University of LausanneAcademic/Hospital5012014
MylanFor profit4412003
PRACSFor profit4012003
Zhejiang UniversityAcademic/Hospital4332020
Ain Shams UniversityAcademic/Hospital3322017
Capital Medical UniversityAcademic/Hospital3112015
Chinese Academy of Medical SciencesAcademic/Hospital3322015
Duke UniversityAcademic/Hospital3232007
Georgetown UniversityAcademic/Hospital3232011
Leiden UniversityAcademic/Hospital3012013
Merck KGaAFor profit3312019
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)Government3122005
National Institutes of Health (NIH)Government3032005
Peking UniversityAcademic/Hospital3222015
University of PennsylvaniaAcademic/Hospital3322013
Aarhus UniversityAcademic/Hospital2212004
Department of Veteran AffairsGovernment2222020
Government of ChinaGovernment2012015
Harvard UniversityAcademic/Hospital2222005
163 organizations
Page 1 / 9

Marketing (51)

OrganizationOrg typeRelationshipDate
AbbVieFor profitNDA2Jul 24, 2002
AbbVieFor profitMKTGJan 18, 2023
Accord ResearchFor profitMKTGOct 19, 2020
AlembicFor profitMKTGMay 20, 2026
AllerganFor profitNDA2Nov 21, 1969
AlvogenFor profitNDA2Oct 24, 2002
Amneal PharmaceuticalsFor profitMKTGFeb 19, 2019
Amneal PharmaceuticalsFor profitSYNFeb 19, 2019
Ani PharmaceuticalsFor profitMKTGOct 28, 2020
Ascent PharmahealthFor profitMKTGJan 18, 2023
Aurobindo PharmaFor profitMKTGJul 16, 2024
AzurityFor profitMKTGNov 30, 2020
AzurityFor profitNDA2Nov 30, 2020
Bristol-Myers SquibbFor profitMKTGDec 7, 2015
Cediprof IncFor profitNDA2Mar 1, 2002
Custopharm IncFor profitMKTGMay 17, 2021
Dr. Reddy's LaboratoriesFor profitMKTGMar 27, 2020
EmpiFor profitMKTGNov 30, 2020
ExeltisFor profitMKTGNov 29, 2024
FreseniusFor profitNDA2Jun 24, 2011
Genus Oncology, LLCFor profitNDA2Jun 6, 2003
HikmaFor profitMKTGMay 17, 2021
HikmaFor profitNDA2May 17, 2021
IBSA Institut Biochimique SAFor profitNDA2Oct 13, 2006
IBSA Institut Biochimique SAFor profitMKTGOct 13, 2006
Jerome Stevens PharmaceuticalsFor profitMKTGAug 21, 2000
Jerome Stevens PharmaceuticalsFor profitNDA2Aug 21, 2000
King PharmaceuticalsFor profitNDA2May 25, 2001
KnollFor profitNDAApr 14, 1955
LloydFor profitNDA2Oct 24, 2002
LupinFor profitMKTGJan 18, 2019
LupinFor profitSYNJan 18, 2019
Macleods Pharmaceuticals, LtdFor profitMKTGDec 21, 2022
Maia Pharms IncFor profitMKTGDec 21, 2018
Merck KGaAFor profitMKTGJun 16, 2005
Merck SeronoFor profitMKTGMay 31, 2002
MylanFor profitMKTGJun 5, 2002
MylanFor profitNDA2Apr 29, 2022
NeogenFor profitMKTGDec 21, 2022
ONESOURCE SPECIALTYFor profitMKTGMar 5, 2025
PH HEALTHFor profitMKTGDec 7, 2015
Par PharmaceuticalsFor profitMKTGDec 7, 2015
Parke-DavisFor profitNDA2—
PiramalFor profitMKTGJun 29, 2016
ProvellFor profitNDA2May 31, 2002
Reguliance LlcFor profitMKTGNov 30, 2020
TevaFor profitSYNMay 10, 2022
TevaFor profitMKTGOct 28, 2020
VistaPharm, Inc.For profitMKTGNov 30, 2020
Zydus Discovery DMCCFor profitMKTGNov 25, 2022
Zydus Discovery DMCCFor profitSYNMar 24, 2023