Pharmacodynamics
Levothyroxine sodium is a synthetic levorotatory isomer of thyroxine, its action identical to thyroxine synthesized by the human thyroid gland. After partial conversion into triiodothyronine (in the liver and kidneys) and passage into the cells of the body, it affects the development and growth of tissues and metabolism. In small doses it has an anabolic effect on protein and fat metabolism. In medium doses, it stimulates growth and development, increases the need for oxygen in tissues, stimulates the metabolism of proteins, fats and carbohydrates, increases the functional activity of the cardiovascular system and the central nervous system.
In large doses, it inhibits the production of thyrotropin-releasing hormone of the hypothalamus and thyroid-stimulating hormone (TSH) of the pituitary gland.
The therapeutic effect is observed after 7-12 days, during the same time the effect persists after discontinuation of the drug. The clinical effect for hypothyroidism appears after 3-5 days. Diffuse goiter decreases or disappears within 3-6 months.
Indications for use
- Hypothyroidism;
- euthyroid goiter;
- as replacement therapy and for the prevention of goiter relapse after surgical interventions on the thyroid gland;
- as suppressive and replacement therapy for malignant neoplasms of the thyroid gland, mainly after surgical treatment;
- diffuse toxic goiter: after achieving a euthyroid state with antithyroid drugs (in the form of combination or monotherapy);
- as a diagnostic tool when performing a thyroid suppression test.
Contraindications for use
- Hypersensitivity to levothyroxine sodium and/or any of the excipients;
- untreated thyrotoxicosis;
- untreated pituitary insufficiency;
- untreated adrenal insufficiency;
- use during pregnancy in combination with antithyroid drugs
Do not start treatment with the drug in the presence of acute myocardial infarction, acute myocarditis, acute pancarditis.
The drug contains lactose, so its use is not recommended for patients with rare hereditary diseases associated with galactose intolerance, lactase deficiency or glucose-galactose malabsorption syndrome.
With caution: the drug should be prescribed for diseases of the cardiovascular system: ischemic heart disease (atherosclerosis, angina pectoris, history of myocardial infarction), arterial hypertension, arrhythmia; for diabetes mellitus, severe long-term hypothyroidism, malabsorption syndrome (dose adjustment may be required), in patients with a predisposition to psychotic reactions.
