Thyroid hormone preparation. Synthetic levorotatory isomer of thyroxine. After partial transformation into triiodothyronine (in the liver and kidneys) and transition 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 tissue oxygen demand, 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 of the pituitary gland.
The therapeutic effect is observed after 7-12 days, during the same time the effect persists after the drug is discontinued. The clinical effect in hypothyroidism appears after 3-5 days. Diffuse goiter decreases or disappears within 3-6 months.
Absorption and distribution
When taken orally, levothyroxine sodium is absorbed mainly in the upper part of the small intestine. Up to 80% of the dose taken is absorbed. Food intake reduces the absorption of levothyroxine sodium.
Cmax in serum is reached approximately 5-6 hours after oral administration.
More than 99% of the absorbed drug binds to serum proteins (thyroxine-binding globulin, thyroxine-binding prealbumin and albumin).
Metabolism and excretion
In various tissues, approximately 80% of levothyroxine is monodeiodinated with the formation of triiodothyronine (T3) and inactive products. Thyroid hormones are metabolized primarily in the liver, kidneys, brain and muscles. A small amount of the drug undergoes deamination and decarboxylation, as well as conjugation with sulfuric and glucuronic acids (in the liver). Metabolites are excreted by the kidneys and through the intestines.
T1 / 2 is 6-7 days.
Pharmacokinetics in special clinical situations
With thyrotoxicosis, T1 / 2 is shortened to 3-4 days, and with hypothyroidism, it is extended to 9-10 days.
Merck KGaA, Russia
1 tab. contains:
Active ingredients: sodium levothyroxine – 75 mcg.
Excipients: corn starch – 25.00 mg, gelatin – 5.00 mg, croscarmellose sodium – 3.50 mg, magnesium stearate – 0.50 mg, lactose monohydrate – 65.925 mg.
- euthyroid goiter;
- as replacement therapy and for the prevention of recurrence of goiter after resection of the thyroid gland;
- thyroid cancer (after surgery);
- diffuse toxic goiter after reaching the euthyroid state with thyreostatics (as combination therapy or monotherapy);
- as a diagnostic tool for a thyroid suppression test.
Application during pregnancy and lactation
- PregnancyDuring pregnancy and breastfeeding, therapy with a drug prescribed for hypothyroidism should be continued. During pregnancy, an increase in the dose of the drug is required due to an increase in the content of thyroxin-binding globulin.
The use of the drug in combination with antithyroid drugs during pregnancy is contraindicated, since taking levothyroxine sodium may require an increase in the doses of antithyroid drugs. Since antithyroid drugs, unlike levothyroxine sodium, can cross the placenta, the fetus may develop hypothyroidism.
- LactationThe amount of thyroid hormone secreted in breast milk during lactation (even when treated with high doses of the drug) is not enough to cause any disturbance in the child.
During the period of breastfeeding, the drug should be taken with caution, strictly in the recommended doses under the supervision of a doctor.
Babies and children under 3 years oldThe daily dose of the drug Eutiroks is given in one dose 30 minutes before the first feeding. The tablet is dissolved in water to a fine suspension, which is prepared immediately before taking the drug.
- Increased individual sensitivity to the drug.
- Untreated thyrotoxicosis.
- Untreated pituitary insufficiency.
- Untreated adrenal insufficiency.
- Acute myocardial infarction.
- Acute myocasditis.
- Acute pancarditis.
- For diseases of the cardiovascular system:
- Cardiac ischemia
- Angina pectoris.
- History of myocardial infarction.
- Arterial hypertension.
- Severe long-term hypothyroidism.
- Malabsorption syndrome (dose adjustment may be required).
- For diseases of the cardiovascular system:
With the correct use of the drug Eutirox under the supervision of a physician, side effects are not observed.
- With increased sensitivity to the drug, allergic reactions may occur.
The development of side effects may be associated with an overdose of the drug.
Levothyroxine sodium enhances the effect of indirect anticoagulants, which may require a dose reduction.
The use of tricyclic antidepressants with levothyroxine sodium can lead to an increase in the effect of antidepressants.
Thyroid hormones can increase the need for insulin and oral hypoglycemic drugs. More frequent monitoring of blood glucose concentration is recommended during the periods of initiation of treatment with levothyroxine sodium, as well as when changing its dosage regimen.
Levothyroxine sodium reduces the action of cardiac glycosides.
With the simultaneous use of cholestyramine, colestipol and aluminum hydroxide, the plasma concentration of levothyroxine sodium decreases by inhibiting its absorption in the intestine. In this regard, levothyroxine sodium should be used 4-5 hours before taking these drugs.
Poi, simultaneous use with anabolic steroids, asparaginase, tamoxifen, pharmacokicetic interaction is possible at the level of binding to plasma proteins.
Simultaneous use with phenytoin, dicumarol, salicylates, clofibrate, furosemide in high doses increases the content of sodium levothyroxine, which is not bound to blood plasma proteins.
Taking estrogen-containing drugs increases the content of thyroxine-binding globulin, which may increase the need for sodium lesemiroxin in some patients.
Somatropin, when used simultaneously with sodium levoltroxin, can accelerate the closure of the epiphyseal growth zones.
Taking phenobarbital, carbamazepine, and rifampicin may increase the clearance of levothyroxine and require an increase in the dose.
How to take, course and dosage
The daily dose is determined individually, depending on the indications.
Eutirox in a daily dose is taken orally in the morning on an empty stomach, at least 30 minutes before a meal, with a pill with a small amount of liquid (half a glass of water) and without chewing.
- When carrying out replacement therapy for hypothyroidism
- In patients under 55 years of age in the absence of cardiovascular diseases: Eutirox is prescribed in a daily dose of 1.6 – 1.8 μg per 1 kg of body weight.
- In patients over 55 years of age or with cardiovascular diseases: 0.9 μg per 1 kg of body weight.
In case of significant obesity, the calculation should be made on the “ideal weight”.
The initial stage of substitution therapy for hypothyroidism Patients without cardiovascular diseases younger than 55 years Initial dose:
women – 75-100 mcg / day
men – 100-150 mcg / day Patients with cardiovascular diseases or older than 55 years
Initial dose – 25 mcg per day
Increase by 25 mcg with an interval of 2 months until the TSH level in the blood normalizes.If
symptoms of the cardiovascular system appear or worsen, correct therapy for cardiovascular diseases
Recommended doses of thyroxine for the treatment of congenital hypothyroidism Age Daily dose of levothyroxine sodium (mcg) Dose of levothyroxine sodium per body weight (mcg / kg) 0-6 months 25-5010-156-12 months 50-756-81-5 years 75-1005-66-12 years 100-1504-5 more than 12 years old100-200
Indications Recommended doses (Eutirox mcg / day) Treatment of euthyroid goiter 75-200 Prevention of relapse after surgical treatment of zugyroid goiter 75-200 In the complex therapy of thyrotoxicosis 50-100 Suppressive therapy for thyroid cancer 150-300 Thyroid suppression testa 3 4 weeks before the test3 test Eutirox 75 mcg / day 75 mcg / day 150-200 mcg / day 150-200 mcg / day
- In patients with severe long-term hypothyroidismTreatment should be started with extreme caution, with small doses – from 12.5 mcg / day, the dose is increased to the maintenance dose at longer intervals – by 12.5 mcg / day every 2 weeks and more often the concentration of TSH in the blood is determined.
- With hypothyroidismEutirox is usually taken throughout life.
- With thyrotoxicosisEutirox is used in complex therapy with antithyroid drugs after reaching the euthyroid state.
In all cases, the duration of drug treatment is determined by the doctor. For accurate dosing, it is necessary to use the most appropriate dosage of Eutirox.
Symptoms: in case of an overdose of the drug, symptoms characteristic of thyrotoxicosis are observed:
- violation of the rhythm of the heart,
- sleep disturbance,
- increased sweating
- increased appetite,
- weight loss,
Treatment: depending on the severity of the symptoms, the doctor may recommend a decrease in the daily dose of the drug, a break in treatment for several days, the appointment of beta-blockers. After the disappearance of side effects, treatment should be started with caution with a lower dose.
In hypothyroidism caused by damage to the pituitary gland, it is necessary to find out whether there is simultaneously an adrenal cortex insufficiency. In this case, replacement therapy with glucocorticosteroids should be started before starting treatment for hypothyroidism with thyroid hormones in order to avoid the development of adrenal insufficiency.
Influence on the ability to drive vehicles and use mechanisms
The drug has no effect on activities related to driving vehicles and operating mechanisms.