Levothyroxine
- Atc Codes:H03AA01
- CAS Codes:25416-65-3#55-03-8#51-48-9
- PHARMGKB ID:25416-65-3#55-03-8#51-48-9
Table of contents
- Brand Names
- Drug Combinations
- Chemistry
- Pharmacologic Category
- Mechanism of Action
- Therapeutic Use
- Pregnancy and Lactation Implications
- Contraindications
- Warnings and Precautions
- Adverse Reactions
- Caution and personalized dose adjustment in patients with the following genotypes
- Other genes that may be involved
- Substrate of
- Induces
- Drug Interactions
- Nutrition/Nutraceutical Interactions
- Dosage
- Pharmacokinetics and Pharmacodynamics
- Special Considerations
Brand Names
Europe
Austria: Euthyrox, L-Thyroxin, Thyrex; Belgium: Elthyrone, Euthyrox, L-Thyroxine; Bulgaria: Euthyrox, L-Thyroxin; Cyprus: T4; Czech Republic: Eltroxin, Euthyrox, Letrox; Denmark: Eltroxin, Euthyrox; Estonia: L-Thyroxin; Finland: Thyroxin; France: L-Thyroxine, Levothyrox; Germany: Berlthyrox, Eferox, Euthyrox, L-Thyrolevi, L-Thyrox, L-Thyroxin, Neothyron, Thevier; Greece: Euthyrox, Levothroid, L-Thyroxin, Medithyrox, T4, Thyro-4, Thyrohormone, Tozot; Hungary: Euthyrox, Letrox, Levothyrox; Ireland: Eltroxin; Italy: Eutirox, Levotirox; Latvia: Euthyrox, L-Thyroxin; Lithuania: Eltroxin, L-Thyroxin; Malta: Eltroxin, Levothyroxine; Netherlands: Eltroxin, Euthyrox, Levothyroxine, Thyrax; Poland: Eferox, Eltroxin, Euthyrox, Letrox, Levoroxin, Novothyral; Portugal: Eutirox, Letequatro, Letter, Thyrax; Romania: Euthyrox, L-Thyroxin, Thyro; Slovakia: Euthyrox, L-Thyroxin; Slovenia: Euthyrox; Spain: Dexnon, Eutirox, Levothroid, Levotiroxina; Sweden: Euthyrox, Levaxin, Levotyroxin; UK: Eltroxin, Levothyroxine.
North America
Canada: Eltroxin, Euthyrox, Levothyroxine, Synthroid; USA: Levo-T, Levothroid, Levothyroxine, Levoxyl, Synthroid, Unithroid.
Latin America
Argentina: Euthyrox, Levotiroxina, L-T 100/150/50, Synthroid, T4 Montpellier; Brazil: Euthyrox, Puran T4, Synthroid, Tetroid, Tiroidin; Mexico: Abutiroi, Cynocuatro, Eutirox, Levotiroxina, Tiroidine.
Asia
Japan: Thyradin-S.
Drug combinations
Levothyroxine and Liothyronine
Chemistry
Levothyroxine Sodium: C~15~H~10~I~4~NNaO~4~ xH~2~O. Mw: 798.85 (anhydrous). (1) L-Tyrosine, O-(4-hydroxy-3,5-diiodophenyl)-3,5-diiodo-, monosodium salt, hydrate; (2) Monosodium L-thyroxine hydrate. CAS-25416-65-3; CAS-55-03-8 (anhydrous); CAS-51-48-9 (L-thyroxine).
Pharmacologic Category
Thyroid Agents. (ATC-Code: H03AA01).
Mechanism of action
Regulates multiple metabolic processes, including augmentation of cellular respiration and thermogenesis, as well as metabolism of proteins, carbohydrates, and lipids. Plays an essential role in normal growth and development and normal maturation of CNS and bone.
Therapeutic use
Replacement or supplemental therapy in hypothyroidism. Pituitary TSH suppression.
Pregnancy and lactiation implications
Untreated maternal hypothyroidism may have adverse effects on fetal growth and development and is associated with higher rate of complications. Treatment should not be discontinued during pregnancy. Minimally excreted in human milk. Adequate levels needed to maintain normal lactation.
Unlabeled use
Contraindications
Hypersensitivity to levothyroxine sodium or any component of the formulation. Recent myocardial infarction or thyrotoxicosis. Uncorrected adrenal insufficiency.
Warnings and precautions
Use with caution in adrenal insufficiency, in diabetes mellitus and insipidus, or in myxedema (symptoms may be exaggerated or aggravated). Use with caution in angina pectoris or other cardiovascular disease. Long-term therapy can decrease bone mineral density. Use with caution in the elderly (compromised cardiovascular function). Use caution in dysphagia or other swallowing disorders. Thyroid supplements ineffective and potentially toxic for weight reduction.