L-thyroxine
L-thyroxine: instructions for use and reviews
- 1. Release form and composition
- 2. Pharmacological properties
- 3. Indications for use
- 4. Contraindications
- 5. Method of application and dosage
- 6. Side effects
- 7. Overdose
- 8. Special instructions
- 9. Application during pregnancy and lactation
- 10. Use in childhood
- 11. Use in the elderly
- 12. Drug interactions
- 13. Analogs
- 14. Terms and conditions of storage
- 15. Terms of dispensing from pharmacies
- 16. Reviews
- 17. Price in pharmacies
Latin name: L-Thyroxin
ATX code: H03AA01
Active ingredient: levothyroxine sodium
Manufacturer: Ozone LLC (Russia)
Description and photo update: 2019-20-08
Prices in pharmacies: from 47 rubles.
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L-thyroxine is a thyroid-stimulating drug, a thyroid hormone.
Release form and composition
The drug is produced in the form of tablets (10 pcs. In blisters, 2, 3, 4, 5, 6, 8 or 10 packages in a cardboard box; 20 or 50 pcs. In polymer containers, 1 container in a cardboard box a pack; 50 pcs. in blisters, 1, 2, 4, 5, 6, 8 or 10 packages in a cardboard box; 50 pcs. in blisters, 1 blister in a cardboard box).
1 tablet contains the active substance: sodium levothyroxine - 50 or 100 mcg.
Pharmacological properties
Pharmacodynamics
The active component of L-Thyroxine is sodium levothyroxine - a synthetic levorotatory isomer of thyroxine, which is partially converted into triiodothyronine in the kidneys and liver, then passes into the cells of the body and affects metabolism, development and growth of tissues.
In small doses, the drug has an anabolic effect on fat and protein metabolism. In medium doses, it increases the tissue oxygen demand, improves the functional activity of the central nervous system and cardiovascular system, stimulates growth and development by improving the metabolism of fats, carbohydrates and proteins. In high doses, levothyroxine sodium inhibits the production of thyroid-stimulating hormone of the pituitary gland and thyrotropin-releasing hormone of the hypothalamus.
The therapeutic effect develops within 7-12 days of taking the drug. The same number of days after its cancellation, the action remains. In hypothyroidism, the clinical effect is manifested in 3-5 days. Diffuse goiter decreases or disappears completely within 3-6 months.
Pharmacokinetics
After entering the gastrointestinal tract, levothyroxine sodium is absorbed practically only in the upper part of the small intestine. The absorption of the drug is about 80% of the dose taken. With the simultaneous intake of food, the absorption of the substance decreases.
The maximum concentration in the blood is reached approximately 5-6 hours after taking the tablet. Levothyroxine sodium is characterized by a very high (at least 99%) connection with serum proteins - albumin, TSPA (thyroxine-binding prealbumin) and TSH (thyroxine-binding globulin). In various tissues, monodeiodination of about 80% of the active substance of the drug occurs with the formation of triiodothyronine (T 3) and inactive products. The metabolism of thyroid hormones is carried out mainly in the kidneys, liver, muscles and brain. A small amount of the drug undergoes decarboxylation and deamination, as well as conjugation with sulfuric and glucuronic acids (in the liver).
The route of excretion of metabolites is through the intestines and kidneys. The half-life is 6-7 days, in patients with thyrotoxicosis - 3-4 days, in patients with hypothyroidism - 9-10 days.
Indications for use
- Euthyroid goiter;
- Hypothyroidism;
- The period after resection of the thyroid gland (for the purpose of preventing goiter recurrence and as replacement therapy);
- Thyroid cancer (after surgery);
- Diffuse toxic goiter (for monotherapy or as part of a complex treatment upon reaching the euthyroid state with thyreostatics);
- Conducting a thyroid suppression test (as a diagnostic tool).
Contraindications
Absolute:
- Acute myocardial infarction, acute myocarditis;
- Untreated thyrotoxicosis;
- Untreated adrenal insufficiency
- Hereditary lactase deficiency or lactose intolerance (impaired absorption of glucose and galactose);
- Hypersensitivity to levothyroxine.
Relative (L-thyroxine tablets must be taken with caution):
- Diseases of the cardiovascular system: arterial hypertension, arrhythmias, coronary heart disease (a history of myocardial infarction, atherosclerosis, angina pectoris);
- Diabetes;
- Severe (long-term) hypothyroidism;
- Malabsorption syndrome (dose adjustment may be required).
Instructions for the use of L-thyroxine: method and dosage
L-thyroxine tablets taken orally on an empty stomach in the morning, at least 1 / 2 hours prior to the meal, liquid squeezed small amount (1 / 2 cups) of water.
The daily dose of L-thyroxine is determined by the attending physician individually and depends on the indications.
For replacement therapy of hypothyroidism in patients under 55 years of age, in the absence of cardiovascular diseases, the recommended daily dose of L-thyroxine is 1.6-1.8 μg / kg of body weight. For patients over 55 years old or in the presence of cardiovascular diseases, the dose is determined at the rate of 0.9 μg / kg of body weight. Patients with severe obesity (BMI - body mass index ≥ 30 kg / m 2) are calculated for the "ideal weight".
At the initial stage of replacement therapy for hypothyroidism, the recommended dose of levothyroxine is:
- Patients without cardiovascular diseases under the age of 55: men - 100-150 mcg / day, women - 75-100 mcg / day;
- Patients over 55 years old and / or with cardiovascular diseases: regardless of gender - 25 mcg / day with a gradual increase in dose (25 mcg with an interval of 2 months) until the normalization of thyroid-stimulating hormone (TSH) in the blood.
In the event of the appearance or aggravation of symptoms from the cardiovascular system, the course of treatment of cardiovascular diseases should be corrected.
Recommended daily doses of L-thyroxine for the treatment of congenital hypothyroidism, depending on the age of the child (dose of levothyroxine / dose of levothyroxine per body weight):
- From birth to 1 / 2 years - 25-50 mg / 10-15mkg / kg;
- From 1 / 2 to 1 year - 50-75 g / 6-8 mcg / kg;
- From 1 to 5 years old - 75-100 mcg / 5-6 mcg / kg;
- From 6 to 12 years old - 100-150 mcg / 4-5 mcg / kg;
- Over 12 years old - 100-200 mcg / 2-3 mcg / kg.
Recommended daily doses of L-thyroxine, depending on the condition / disease:
- Therapy for euthyroid goiter - 75-200 mcg;
- Prevention of relapse after surgical treatment of euthyroid goiter - 75-200 mcg;
- Thyrotoxicosis (as part of complex therapy) - 50-100 mcg;
- Thyroid cancer (for suppressive therapy) - 150-300 mcg;
- Carrying out a thyroid suppression test - 3-4 weeks before the test - 75 μg, 1-2 weeks before the test - 150-200 μg.
Children from birth to 3 years of daily dose of levothyroxine is given for 1 / 2 hours before the first feeding (at once). Immediately before use, the tablet must be dissolved in water until a fine suspension is formed.
In the case of hypothyroidism, L-thyroxine is usually taken throughout life. For the treatment of thyrotoxicosis, the drug is used in combination with antithyroid drugs after reaching the euthyroid state. The duration of the course of therapy with levothyroxine for any condition / disease is determined by the attending physician.
Side effects
When using L-thyroxine in compliance with all recommendations and under medical supervision, no side effects were observed.
In case of hypersensitivity to levothyroxine, allergic reactions are possible. Other side effects can develop only with an overdose of the drug.
Overdose
In case of an overdose, symptoms typical of thyrotoxicosis occur: increased sweating, heart pain, heart rhythm disturbances, heart palpitations, tremors, increased appetite, diarrhea, sleep disturbances, anxiety, weight loss.
Depending on the severity of the overdose symptoms, the doctor may recommend a decrease in the daily dose of L-Thyroxine, a short (several days) break in its intake and / or the use of beta-blockers. After normalization of the condition, the drug should be taken with caution, with a minimum dose.
special instructions
In the case of hypothyroidism caused by damage to the pituitary gland, it is necessary to diagnose and find out if there is simultaneously an insufficiency of the adrenal cortex. If the result is positive, it is necessary to start replacement therapy with corticosteroids (glucocorticosteroids) before taking thyroid hormones for the treatment of hypothyroidism in order to avoid the development of acute adrenal insufficiency.
Periodically, the concentration of TSH in the blood should be monitored, an increase in this indicator indicates an insufficient dose of L-thyroxine.
Levothyroxine does not affect the concentration of attention and the speed of psychomotor reactions necessary to control complex mechanisms and vehicles.
Application during pregnancy and lactation
Hypothyroidism therapy during pregnancy and lactation should be continued. During pregnancy, the TSH level rises, so an increase in the dose of L-Thyroxine is required.
The use of levothyroxine sodium during pregnancy is contraindicated in combination with antithyroid drugs, since their dose may need to be increased while taking L-Thyroxine. In addition, unlike levothyroxine sodium, antithyroid drugs can penetrate the placenta, resulting in the development of hypothyroidism in the fetus.
The amount of thyroid hormone that is excreted in breast milk (even when taking the drug in high doses) is small, so it is not capable of causing any disturbances in the child. However, women who are breastfeeding should be monitored by a doctor and strictly adhere to the recommendations.
Pediatric use
According to the instructions, L-Thyroxine is approved for use in pediatrics in accordance with the dosage regimen according to age.
Use in the elderly
L-Thyroxine is used according to indications in elderly patients in accordance with the doctor's recommendations.
Drug interactions
The mutual influence of the following substances / drugs and levothyroxine with simultaneous use:
- Insulin and oral hypoglycemic drugs - an increase in their dose may be required (at the beginning of therapy with levothyroxine sodium, as in the case of changing the dosage regimen, blood glucose concentration should be checked more often);
- Indirect anticoagulants, tricyclic antidepressants - their effect is enhanced (dose reduction may be required);
- Colestipol, cholestyramine, aluminum hydroxide - reduce the concentration of levothyroxine sodium in the blood plasma due to a decrease in the rate of its absorption in the intestine;
- Anabolic steroids, asparaginase, tamoxifen - there is a possibility of pharmacokinetic interaction at the level of protein binding;
- Cardiac glycosides - their effectiveness decreases;
- Salicylates, clofibrate, furosemide (in high doses), phenytoin - increase the plasma levels of sodium levothyroxine not bound to proteins and free thyroxine (T4); phenytoin reduces the volume of levothyroxine bound to proteins by 15%, the concentration of T4 - by 25%;
- Estrogen-containing drugs - increase the amount of thyroxine-binding globulin, which may increase the need for levothyroxine in some patients;
- Growth hormone - it is possible to accelerate the closure of the epiphyseal growth zones;
- Phenobarbital, carbamazepine and rifampicin - can increase the clearance of sodium levothyroxine, as a result of which an increase in its dose is likely;
- Aminoglutethimide, amiodarone, paraaminosalicylic acid (PASK), antithyroid drugs, β-blockers, ethionamide, carbamazepine, chloral hydrate, levodopa, diazepam, dopamine, metoclopramide, somatostatin, lovastatin - have an effect on thyroxism and L-distribution.
Analogs
Analogs of L-Thyroxin are: Bagothyrox, Levothyroxin, Eutirox, L-Thyroxin 50 Berlin-Chemie, L-Tyroxin 75 Berlin-Chemie, L-Tyroxin 100 Berlin-Chemie, L-Thyroxin 150 Berlin-Chemie.
Terms and conditions of storage
Store in a dry, dark place, out of reach of children, at a temperature not exceeding 25 ° C.
The shelf life is 3 years.
Terms of dispensing from pharmacies
Dispensed by prescription.
Reviews of L-Thyroxine
Reviews of L-Thyroxine are mostly good. Patients indicate that the drug normalizes the balance of thyroid hormones, and this has a positive effect on overall well-being. Some negative messages contain complaints about the development of side effects.
Despite the fact that L-Thyroxine is intended for the treatment of endocrinological diseases, its anabolic effect is often used for weight loss purposes. Patients claim that the remedy helps to correct body weight, especially when supplemented with a low-carb diet. Doctors, however, emphasize that levothyroxine sodium can only be used with reduced thyroid function. Excess weight is often one of the signs of malfunctioning of this organ, therefore, a decrease in body fat can be considered a kind of side effect of the drug. Taking L-Thyroxin exclusively for weight loss is strictly contraindicated, since it is fraught with various health problems. In this regard, the drug should be prescribed only by a doctor after establishing an accurate diagnosis.
Price for L-Thyroxine in pharmacies
Prices for L-Thyroxine, depending on the dosage, can be: 50 tablets of 50 μg each - from 80 rubles, 50 tablets of 100 μg - from 100 rubles, 100 tablets of 100 μg - from 120 rubles.
L-thyroxine: prices in online pharmacies
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Drug name Price Pharmacy |
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L-Thyroxine 100 mcg tablets 100 pcs. RUB 47 Buy |
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L-Thyroxin 100 Berlin-Chemie 100 mcg tablets 50 pcs. RUB 63 Buy |
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L-Thyroxin 50 Berlin-Chemie 50 mcg tablets 50 pcs. 74 RUB Buy |
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L-Thyroxin 50 Berlin-Chemie tablets 50mcg 50 pcs RUB 76 Buy |
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L-Thyroxine 100 mcg tablets 50 pcs. 77 RUB Buy |
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L-Thyroxine 50 mcg tablets 50 pcs. 77 RUB Buy |
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L-Thyroxin 100 Berlin-Chemie tablets 100mcg 50 pcs. RUB 87 Buy |
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L-Thyroxin 150 Berlin-Chemie 150 mcg tablets 100 pcs. RUB 98 Buy |
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Reviews L-Thyroxin 150 Berlin-Chemie RUB 98 Buy |
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L-Thyroxin 125 Berlin-Chemie 125 mcg tablets 100 pcs. RUB 100 Buy |
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Reviews L-Thyroxin 125 Berlin-Chemie RUB 100 Buy |
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L-Thyroxin 75 Berlin-Chemie 75 mcg tablets 100 pcs. RUB 111 Buy |
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Reviews L-Thyroxin 75 Berlin-Chemie RUB 111 Buy |
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L-Thyroxin 100 Berlin-Chemie 100 mcg tablets 100 pcs. 116 RUB Buy |
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L-Thyroxin 100 Berlin-Chemie tablets 100mcg 100 pcs. 119 RUB Buy |
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L-Thyroxin 75 Berlin-Chemie tablets 75mcg 100 pcs. 120 RUB Buy |
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L-Thyroxin 150 Berlin-Chemie tablets 150mcg 100 pcs. 140 RUB Buy |
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L-Thyroxin 125 Berlin-Chemie 125mcg tablets 100 pcs. 152 RUB Buy |
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Anna Kozlova Medical journalist About the author
Education: Rostov State Medical University, specialty "General Medicine".
Information about the drug is generalized, provided for informational purposes only and does not replace the official instructions. Self-medication is hazardous to health!
