Levothyroxine


Description

Levothyroxine is a synthetically produced form of thyroxine, a major endogenous hormone secreted by the thyroid gland.[13] Also known as L-thyroxine or the brand n...

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Pharmacology

Indication

Levothyroxine is indicated as replacement therapy in primary (thyroidal), secondary (pituitary) and... Read more

Pharmacodynamic

Oral levothyroxine is a synthetic hormone that exerts the same physiologic effect as endogenous T Read more

Mechanismofaction

Levothyroxine is a synthetically prepared levo-isomer of the thyroid hormone thyroxine (T4 Read more

Absorption

Absorption of orally administered T4 from the gastrointestinal tract ranges from 40% to 80% with the... Read more

Proteinbinding

Circulating thyroid hormones are greater than 99% bound to plasma proteins, including thyroxine-bind... Read more

Volumeofdistribution

Information currently not available.

Clearance

Information currently not available.

Halflife

T4 half-life is 6 to 7 days. T3 half-life is 1 to 2 days.[ Read more

Routeofelimination

Thyroid hormones are primarily eliminated by the kidneys. A portion of the conjugated hormone reache... Read more

Toxicity

LD50=20 mg/kg (orally in rat). Hypermetabolic state indistinguishable from thyrotoxicosis... Read more


Adverse Effects

Effect Regions Age Groups Incidences Evidence Type
Abdominal Cramps US
Varying Reports
Vomiting US
Varying Reports
Hair Loss US
Varying Reports
Elevation in liver function tests US
Varying Reports
Cardiac Arrest US
Varying Reports
Myocardial Infarction US
Varying Reports
Diarrhea US
Varying Reports
Dyspnea US
Varying Reports
Urticaria US
Varying Reports
Seizure US
Varying Reports
Skin Rash US
Varying Reports
Pruritis US
Varying Reports
Decreased bone mineral density US
Varying Reports
Flushing US
Varying Reports
Impaired fertility US
Varying Reports
Menstrual Irregularities US
Varying Reports
Irritability US
Varying Reports
Emotional Lability US
Varying Reports
Insomnia US
Varying Reports
Tremors US
Varying Reports
Headache US
Varying Reports
Hyperactivity US
Varying Reports
Nervousness US
Varying Reports
Anxiety US
Varying Reports
Increased pulse US
Varying Reports
Increased blood pressure US
Varying Reports
Heart Failure US
Varying Reports
Angina US
Varying Reports
Muscle Weakness US
Varying Reports
Palpitations US
Varying Reports
Tachycardia US
Varying Reports
Arrhythmias US
Varying Reports
Heat Intolerance US
Varying Reports
Insomnia US
Varying Reports
Tremors US
Varying Reports
Angina Pectoris US
Varying Reports
Cardiac Arrhythmias US
Varying Reports
Increased blood pressure US
Varying Reports
Increased pulse US
Varying Reports
Tachycardia US
Varying Reports
Excessive sweating US
Varying Reports
Fever US
Varying Reports
Heat Intolerance US
Varying Reports
Weight Loss US
Varying Reports
Increased appetite US
Varying Reports
Fatigue US
Varying Reports
Menstrual Irregularities US
Varying Reports
Fever US
Varying Reports
Abdominal Cramps US
Varying Reports
Sweating US
Varying Reports

Contraindications

  • Route:
    • Oral
  • Regions: Canada
  • Patient Conditions:
      • Name: Untreated subclinical or overt thryrotoxicosis
      • Drugbank Id: DBCOND0107743
  • Route:
    • Oral
  • Regions: Canada
  • Patient Conditions:
      • Name: Acute Myocardial Infarction
      • Drugbank Id: DBCOND0030399
      • Modification Of:
        • Base:
          • Name: Myocardial Infarction
          • Drugbank Id: DBCOND0027900
        • Severity:
          • Includes:
            • acute
  • Route:
    • Intravenous
    • Intramuscular
  • Dose Form:
    • Injection
  • Hypersensitivity:
    • false
  • Regions: US
  • Route:
    • Oral
  • Regions: US
  • Patient Conditions:
      • Name: Uncorrected adrenal insufficiency
      • Drugbank Id: DBCOND0107744

Food Interactions

  • Absorption increased in fasting state and decreased in malabsorption states.
  • Consistent administration in relation to meals is recommended.
  • No iron or calium carbonate within 4 hours of taking this medication.
  • Oral administration with infant soybean formula, soybean flour, cotton seed meal, walnuts, foods containing large amounts of fiber, ferrous sulfate, and antacids may decrease drug absorption.
  • Take 30-60 minutes before breakfast.

Interactions

Type in a drug name to check for interaction with Levothyroxine

The metabolism of Levothyroxine can be decreased when combined with (R)-warfarin.
The metabolism of Levothyroxine can be decreased when combined with (S)-Warfarin.
The risk or severity of adverse effects can be increased when 2,5-Dimethoxy-4-ethylamphetamine is combined with Levothyroxine.
The risk or severity of adverse effects can be increased when 2,5-Dimethoxy-4-ethylthioamphetamine is combined with Levothyroxine.
The metabolism of Levothyroxine can be decreased when combined with 3,5-diiodothyropropionic acid.
The risk or severity of adverse effects can be increased when 4-Bromo-2,5-dimethoxyamphetamine is combined with Levothyroxine.
The metabolism of Levothyroxine can be decreased when combined with 4-hydroxycoumarin.
The metabolism of Levothyroxine can be decreased when combined with 5-androstenedione.
The therapeutic efficacy of Levothyroxine can be decreased when used in combination with 5-fluorouridine.
The metabolism of Levothyroxine can be decreased when combined with 6-Deoxyerythronolide B.
The metabolism of Levothyroxine can be decreased when combined with 6-O-benzylguanine.
The metabolism of Levothyroxine can be decreased when combined with 7-ethyl-10-hydroxycamptothecin.
The metabolism of Levothyroxine can be decreased when combined with 9-aminocamptothecin.
The metabolism of Levothyroxine can be increased when combined with Abatacept.
Levothyroxine may increase the anticoagulant activities of Abciximab.
The metabolism of Levothyroxine can be decreased when combined with Abemaciclib.
The metabolism of Levothyroxine can be decreased when combined with Abiraterone.
The metabolism of Levothyroxine can be decreased when combined with Acalabrutinib.
The risk or severity of adverse effects can be increased when Acebutolol is combined with Levothyroxine.
The metabolism of Levothyroxine can be decreased when combined with Acenocoumarol.

References

  • 1 . Uchino H, Kanai Y, Kim DK, Wempe MF, Chairoungdua A, Morimoto E, Anders MW, Endou H: Transport of amino acid-related compounds mediated by L-type amino acid transporter 1 (LAT1): insights into the mechanisms of substrate recognition. Mol Pharmacol. 2002 Apr;61(4):729-37. [PubMed: 11901210]
  • 2 . Cheng SY, Leonard JL, Davis PJ: Molecular aspects of thyroid hormone actions. Endocr Rev. 2010 Apr;31(2):139-70. doi: 10.1210/er.2009-0007. Epub 2010 Jan 5. [PubMed: 20051527]
  • 3 . Chon DA, Reisman T, Weinreb JE, Hershman JM, Leung AM: Concurrent Milk Ingestion Decreases Absorption of Levothyroxine. Thyroid. 2018 Apr;28(4):454-457. doi: 10.1089/thy.2017.0428. Epub 2018 Mar 28. [PubMed: 29589994]
  • 4 . Tang R, Wang J, Yang L, Ding X, Zhong Y, Pan J, Yang H, Mu L, Chen X, Chen Z: Subclinical Hypothyroidism and Depression: A Systematic Review and Meta-Analysis. Front Endocrinol (Lausanne). 2019 Jun 4;10:340. doi: 10.3389/fendo.2019.00340. eCollection 2019. [PubMed: 31214119]
  • 5 . Gottwald-Hostalek U, Uhl W, Wolna P, Kahaly GJ: New levothyroxine formulation meeting 95-105% specification over the whole shelf-life: results from two pharmacokinetic trials. Curr Med Res Opin. 2017 Feb;33(2):169-174. doi: 10.1080/03007995.2016.1246434. Epub 2016 Oct 21. [PubMed: 27718637]
  • 6 . Osmak-Tizon L, Poussier M, Cottin Y, Rochette L: Non-genomic actions of thyroid hormones: Molecular aspects. Arch Cardiovasc Dis. 2014 Apr;107(4):207-11. doi: 10.1016/j.acvd.2014.02.001. Epub 2014 Mar 26. [PubMed: 24680385]
  • 7 . Klein I, Ojamaa K: Thyroid hormone and the cardiovascular system. N Engl J Med. 2001 Feb 15;344(7):501-9. doi: 10.1056/NEJM200102153440707. [PubMed: 11172193]
  • 8 . Kaplan MM, Breitbart R: Conversion of thyroxine to triiodothyronine in the anterior pituitary gland and the influence of this process on thyroid status. Horm Metab Res Suppl. 1984;14:79-85. [PubMed: 6595194]
  • 9 . Hammes SR, Davis PJ: Overlapping nongenomic and genomic actions of thyroid hormone and steroids. Best Pract Res Clin Endocrinol Metab. 2015 Aug;29(4):581-93. doi: 10.1016/j.beem.2015.04.001. Epub 2015 Apr 22. [PubMed: 26303085]
  • 10 . Jonklaas J, Bianco AC, Bauer AJ, Burman KD, Cappola AR, Celi FS, Cooper DS, Kim BW, Peeters RP, Rosenthal MS, Sawka AM: Guidelines for the treatment of hypothyroidism: prepared by the american thyroid association task force on thyroid hormone replacement. Thyroid. 2014 Dec;24(12):1670-751. doi: 10.1089/thy.2014.0028. [PubMed: 25266247]
  • 11 . Davis PJ, Leonard JL, Davis FB: Mechanisms of nongenomic actions of thyroid hormone. Front Neuroendocrinol. 2008 May;29(2):211-8. doi: 10.1016/j.yfrne.2007.09.003. Epub 2007 Oct 5. [PubMed: 17983645]
  • 12 . Bergh JJ, Lin HY, Lansing L, Mohamed SN, Davis FB, Mousa S, Davis PJ: Integrin alphaVbeta3 contains a cell surface receptor site for thyroid hormone that is linked to activation of mitogen-activated protein kinase and induction of angiogenesis. Endocrinology. 2005 Jul;146(7):2864-71. doi: 10.1210/en.2005-0102. Epub 2005 Mar 31. [PubMed: 15802494]
  • 13 . FDA Label - levothyroxine [File]
  • 14 . American Association of Clinical Endocrinologists (AACE): Clinical Practice Guidelines for Hypothyroidism in Adults [File]

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