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QuickView for Levothyroxine (compound)


PubChem
Name: Thyroxine
PubChem Compound ID: 5819
Description: The major hormone derived from the thyroid gland. Thyroxine is synthesized via the iodination of tyrosines (MONOIODOTYROSINE) and the coupling of iodotyrosines (DIIODOTYROSINE) in the THYROGLOBULIN. Thyroxine is released from thyroglobulin by proteolysis and secreted into the blood. Thyroxine is peripherally deiodinated to form TRIIODOTHYRONINE which exerts a broad spectrum of stimulatory effects on cell metabolism.
Molecular formula: C15H11I4NO4
Molecular weight: 776.87 g/mol
Synonyms:
Thyroxine (VAN); MLS000028647; 587-29-1; beta-((3,5-Diiodo-4-hydroxyphenoxy)-3,5-diiodophenyl)alanine; Thyratabs; Tyrosine, O-(4-hydroxy-3,5-diiodophenyl)-3,5-diiodo-, labeled with iodine-125; SDCCGMLS-0066571.P001; 4-(4-hydroxy-3,5-diiodophenoxy)-3,5-diiodo-L-phenylalanine; EINECS 200-101-1; Thyroxine, L- (8CI).
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DrugBank
Identification
Name: Thyroxine
Name (isomeric): DB00451
Drug Type: small molecule
Description: The major hormone derived from the thyroid gland. Thyroxine is synthesized via the iodination of tyrosines (MONOIODOTYROSINE) and the coupling of iodotyrosines (DIIODOTYROSINE) in the THYROGLOBULIN. Thyroxine is released from thyroglobulin by proteolysis and secreted into the blood. Thyroxine is peripherally deiodinated to form TRIIODOTHYRONINE which exerts a broad spectrum of stimulatory effects on cell metabolism.
Synonyms:
L-Thyroxine; Tetraiodothyronine; THX; T4 levothyroxine; Levothyroxin; L-Thryoxin; Levo-t; 3,3',5,5'-Tetraiodo-L-thyronine; Laevothyroxinum; O-(4-Hydroxy-3,5-diidophenyl)-3,5-diiodo-L-tyrosine.
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Brand: Thyreoideum, Levothyrox, Thyroxinal, Eltroxin, Laevoxin, Unithroid, Levaxin, Thyroxevan, Thyroxin, Thyrax, Euthyrox, Thyro-tabs, Novothyrox, Oroxine, Synthroid, Levoxine, Synthroid Sodium, Letter, Levolet, Levoxyl, Levothroid, Thyratabs
Brand name mixture: Liotrix(Levothyroxine + Liothyronine), Thyrolar(Levothyroxine + Liothyronine)
Category: Antithyroid Agents
CAS number: 51-48-9
Pharmacology
Indication: For use alone or in combination with antithyroid agents to treat hypothyroidism, goiter, chronic lymphocytic thyroiditis, myxedema coma, and stupor.
Pharmacology:
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 effect...
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Mechanism of Action:
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 thyroxi...
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Absorption: Bioavailability varies from 48% to 80%. Human studies have confirmed the importance of an intact jejunum and ileum for levothyroxine absorption and have shown some absorption from the duodenum.
Protein binding: > 99% to serum proteins, including thyroxine-binding globulin (TBG), thyroxine-binding prealbumin (TBPA), and albumin (TBA)
Biotransformation: Approximately 70% of secreted T4 is deiodinated to equal amounts of T3 and reverse triiodothyronine (rT3), which is calorigenically inactive. Elimination of T4 and T3 involves hepatic conjugation to glucuronic and sulfuric acids. The hormones undergo enterohepatic circulation as conjugates are hydrolyzed in the intestine and reabsorbed. Conjugated compounds that reach the colon are hydrolyzed and eliminated as free compounds in the feces. Other minor T4 metabolites have been identified.
Route of elimination: Thyroid hormones are primarily eliminated by the kidneys.
Half Life: T4, 6 to 7 days. T3, 1 to 2 days.
Toxicity: LD50=20 mg/kg (orally in rat). Hypermetabolic state indistinguishable from thyrotoxicosis of endogenous origin. Symptoms of thyrotoxicosis include weight loss, increased appetite, palpitations, nervousness, diarrhea, abdominal cramps, sweating, tachycardia, increased pulse and blood pressure, cardiac arrhythmias, tremors, insomnia, heat intolerance, fever, and menstrual irregularities.
Affected organisms: Humans and other mammals
Interactions
Food interaction:
Absorption increased in fasting state and decreased in malabsorption states.
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.
No iron or calium carbonate within 4 hours of taking this medication.
Take 30-60 minutes before breakfast.
Consistent administration in relation to meals is recommended.
Drug interaction:
Calcium AcetateCalcium salts such as calcium acetate may diminish the therapeutic effect of thyroid products such as levothyroxine. Separate the doses of the thyroid product and the oral calcium supplement by at least 4 hours. Monitor for decreased therapeutic effects of thyroid products if an oral calcium supplement is initiated/dose increased, or increased effects if an oral calcium supplement is discontinued/dose decreased.
WarfarinLevothyroxine may contribute to the anticoagulant effect of warfarin by increasing the metabolism of vitamin K-dependent clotting factors. Monitor for changes in prothrombin time and anticoagulant effects if levothyroxine is initiated, discontinued or dose changed.
ColestipolThe resin, colestipol, decreases the absorption of the thyroid hormone, levothyroxine.
DicumarolThe thyroid hormone, levothyroxine, increase the anticoagulant effect of dicumarol.
CholestyramineThe resin, cholestyramine, decreases the absorption of the thyroid hormone, levothyroxine.
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