Levothyroxine
Levothyroxine: 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 the elderly
- 11. Drug interactions
- 12. Analogs
- 13. Terms and conditions of storage
- 14. Terms of dispensing from pharmacies
- 15. Reviews
- 16. Price in pharmacies
Latin name: Levothyroxine
ATX code: H03AA01
Active ingredient: levothyroxine sodium
Producer: Borisov plant of medical preparations (Belarus), JSC "Valenta Pharmaceuticals" (Russia)
Description and photo update: 2019-16-08
Levothyroxine is a hormonal drug used to diagnose, treat and prevent thyroid diseases.
Release form and composition
Levothyroxine is produced in the form of tablets: flat-cylindrical, white or white with a creamy shade (10 or 25 pcs. In blisters, 1, 2 or 5 packs in a cardboard box).
The composition of 1 tablet includes:
- Active ingredient: sodium levothyroxine - 25, 50 or 100 mcg;
- Auxiliary components: milk sugar (lactose), talc, Kollidon 25, calcium hydrogen phosphate dihydrate, magnesium stearate.
Pharmacological properties
Pharmacodynamics
Levothyroxine is a synthetic thyroid hormone [levorotatory form of thyroxine (T4)], which, when administered from the outside, compensates for the deficiency of the hormone produced by the thyroid gland. By increasing the tissue oxygen demand, it stimulates their growth and differentiation, and also increases the level of basal metabolism of fats, carbohydrates and proteins. When taken in small doses, levothyroxine is characterized by an anabolic, and in significant doses, a catabolic effect. The substance helps to activate energy processes, which has a positive effect on the functions of the liver, kidneys, cardiovascular system and central nervous system.
Levothyroxine is involved in metabolic processes in the liver and passes into the active form of T3, which affects metabolism and tissue formation. The mechanism of action is explained by binding to the genome and normalization of metabolism in mitochondria. The use of the drug in high doses reduces the production of thyroid-stimulating hormone. It is also used to treat hypothyroidism, and the effect of treatment is observed 3-4 days after the start of therapy. When Levothyroxine is prescribed to patients with diffuse goiter, there is a decrease in the size of the thyroid gland in about 3–6 months.
Pharmacokinetics
After oral administration, approximately 80% of the levothyroxine dose is absorbed in the upper small intestine. The absorption of the drug decreases after a meal. The maximum content of the substance in the blood plasma is recorded after 6 hours. The degree of binding to plasma proteins is 99%.
The therapeutic effect occurs 3-5 days after the start of therapy. The metabolism of levothyroxine is carried out in the tissues of the brain, liver, kidneys, muscles with the formation of triiodothyronine, which has a more pronounced hormonal activity. The half-life is 6-7 days. Levothyroxine is eliminated through the kidneys and excreted in the bile (up to 15% of the administered dose).
Indications for use
- Euthyroid goiter;
- Hypothyroidism;
- Goiter after removal of the thyroid gland (as replacement therapy and as prevention);
- Thyroid cancer (after surgery);
- Diffuse toxic goiter: after reaching the euthyroid state against the background of thyreostatic treatment (as monotherapy or simultaneously with other drugs).
Also, the drug is used as a diagnostic tool for the thyroid suppression test.
Contraindications
- Untreated thyrotoxicosis;
- Acute myocarditis, acute myocardial infarction;
- Untreated adrenal insufficiency;
- Hypersensitivity to drug components.
According to the instructions, Levothyroxine should be taken with caution in the presence of cardiovascular diseases: ischemic heart disease (atherosclerosis, angina pectoris, a history of myocardial infarction), arrhythmias, arterial hypertension. You also need to be careful when using Levothyroxine in patients with diabetes mellitus, long-term hypothyroidism with a severe course, malabsorption syndrome (dose adjustment may be required).
Therapy for hypothyroidism during pregnancy should be continued. Concomitant use with thyreostatics is contraindicated. For nursing women, the drug should be taken with caution under the supervision of a doctor, with strict adherence to the prescribed doses.
Instructions for the use of Levothyroxine: method and dosage
Levothyroxine is taken orally, in the morning on an empty stomach (30 minutes before meals), with a small amount of liquid (1/2 glass of water). Do not chew the tablet.
The daily dose of the drug is determined individually based on the indications.
During the substitution treatment of hypothyroidism for patients under 55 years of age without cardiovascular diseases, Levothyroxine is prescribed in a daily dose of 1.6-1.8 μg / kg of body weight; patients from 55 years old or in the presence of cardiovascular system disorders - 0.9 μg / kg body weight. Calculation of the dose for significant obesity should be done on the "ideal weight".
At the initial stage of replacement therapy for hypothyroidism in patients under 55 years of age without cardiovascular diseases, the drug is prescribed in the following daily doses:
- Women: 75-100 mcg
- Men: 100-150 mcg.
In the presence of cardiovascular diseases or patients over the age of 55, Levothyroxine is prescribed at an initial dose of 25 mcg per day. Until the level of thyroid-stimulating hormone in the blood is normalized, the dose is increased by 25 μg once every 2 months. If cardiac symptoms develop or worsen, cardiac treatment should be corrected.
When treating congenital hypothyroidism, Levothyroxine is prescribed depending on age (daily dose / dose based on body weight):
- 0-6 months: 25-50 mcg / 10-15 mcg / kg;
- 6-12 months: 50-75 mcg / 6-8 mcg / kg;
- 1-5 years: 75-100 mcg / 5-6 mcg / kg;
- 6-12 years old: 100-150 mcg / 4-5 mcg / kg;
- Over 12 years: 100-200 mcg / 2-3 mcg / kg.
For other indications, the following dosing regimen is prescribed:
- Euthyroid goiter (treatment and prevention of relapse after surgical treatment): 75-200 mcg per day;
- Thyrotoxicosis (complex therapy): 50-100 mcg per day;
- Thyroid cancer (suppressive therapy): 50-300 mcg per day.
Before the thyroid suppression test, Levothyroxine is prescribed at 75 mcg per day 4 and 3 weeks before the test, for 2 and 1 weeks - 150-200 mcg per day.
The daily dose of Levothyroxine for infants is given 30 minutes before the first feeding in one dose. The tablet should be dissolved in water to a fine suspension (prepared immediately before taking).
In patients with severe long-term hypothyroidism, therapy should be started with extreme caution with small doses (12.5 mcg per day). An increase in the dose to a maintenance dose is carried out at longer intervals - every 2 weeks by 12.5 μg per day. Such patients need to more often determine the level of thyroid-stimulating hormone in the blood.
Levothyroxine for hypothyroidism is taken, as a rule, throughout life. In case of thyrotoxicosis, the drug should be used simultaneously with thyreostatics after reaching the euthyroid state.
In all cases, the duration of therapy is determined by the doctor.
Side effects
With the correct use of Levothyroxine, side effects, as a rule, do not develop.
In case of hypersensitivity to the components of the drug, allergic reactions may occur.
Overdose
In case of an overdose, a thyrotoxic crisis is observed, manifested by symptoms such as hyperhidrosis, tachycardia, weight loss, exophthalmos, and tremor of the fingers. In this case, it is necessary to reduce the dose of the drug. In case of acute intoxication, plasmapheresis and gastric lavage are recommended. It is also allowed to prescribe glucocorticosteroids, cholestyramine, cardiac glycosides, beta-blockers and oxygen therapy. The use of antithyroid drugs is contraindicated.
special instructions
In hypothyroidism caused by damage to the pituitary gland, it is necessary to find out whether the disease is accompanied by insufficiency of the adrenal cortex. In this case, in order to avoid the development of acute adrenal insufficiency, replacement therapy with glucocorticosteroids must be started before the initiation of therapy for hypothyroidism with thyroid hormones.
Application during pregnancy and lactation
In pregnant patients and nursing mothers, Levothyroxine is used only under the supervision of a specialist. The combination of the drug with thyrostatic drugs is contraindicated, since it increases the risk of developing hypothyroidism in the fetus.
Use in the elderly
In elderly patients suffering from hypothyroidism for a long time, it is recommended to start treatment with the drug gradually.
Drug interactions
With the simultaneous use of Levothyroxine with certain drugs, the following effects may occur:
- Indirect anticoagulants: increasing their action (may require a decrease in their dose);
- Tricyclic antidepressants: increasing their action;
- Estrogen-containing drugs: an increase in the content of thyroxine-binding globulin (an increase in the dose of levothyroxine sodium may be required);
- Insulin, oral hypoglycemic drugs: increased need for them;
- Cardiac glycosides: decrease in their action;
- Cholestyramine, colestipol, aluminum hydroxide: decrease in the plasma concentration of sodium levothyroxine;
- Anabolic steroids, asparaginase, tamoxifen: pharmacokinetic interaction at the level of protein binding;
- Phenytoin, salicylates, clofibrate, furosemide (in high doses): an increase in the content of sodium levothyroxine, which is not associated with blood plasma proteins;
- Growth hormone: accelerating the closure of the epiphyseal growth zones;
- Phenobarbital, carbamazepine, rifampicin: an increase in the clearance of sodium levothyroxine (an increase in its dose may be required).
Analogs
Levothyroxine analogues are: Eutirox, Bagothyrox, L-thyroxine.
Terms and conditions of storage
Store in a dark, dry place out of reach of children at temperatures up to 25 ° C.
Shelf life is 2 years.
Terms of dispensing from pharmacies
Available without a prescription.
Reviews about Levothyroxine
Reviews about Levothyroxine, which are left by experts, indicate that treatment must be carried out, be sure to control the content of TSH. Its increase indicates the need to increase the dose. At the initial stage, doctors advise taking into account the patient's age and the presence of diseases of the cardiovascular system. Metabolic status is best restored gradually, starting at the lowest dose. Most patients have to take Levothyroxine all their lives, since hypothyroidism cannot be completely cured. Patients report that improvement occurs in a few weeks, and the maximum effect is achieved 3–6 months after starting therapy.
Patients claim that the drug is well tolerated and, with the correct dose selection, does not affect the function of the cardiovascular system. However, there are reports of adverse reactions manifested in the form of insomnia, hand tremors, angina pectoris, arrhythmias, tachycardia. If we compare Levothyroxine and its analogue Eutirox (made in Germany), then with an identical active substance and the same effect on the body, the latter has a wider choice of doses, which allows the doctor to choose the most optimal treatment depending on the clinical picture.
Some people use Levothyroxine for weight loss when doing bodybuilding, because it stimulates the central nervous system, increases efficiency, promotes fat burning, and intensifies heat production and metabolic processes. Its effectiveness is greater than that of most fat burners. It is noted that using it for such purposes is preferable to triiodothyronine. However, occasionally taking the drug does not give results, especially if the patient adheres to a low-carbohydrate diet, which inhibits the conversion of levothyroxine to triiodothyronine. The duration of the course of treatment for weight loss should be from 4 to 6 weeks. Experts recommend starting the use of Levothyroxine with a daily dose of 50 mcg, dividing it into 2 doses during the first half of the day. Then the dose is increased to 150–300 mcg per day, dividing it into 2–3 doses. Riboxin, asparkam, and beta blockers are prescribed for heart pain, heart palpitations, anxiety, and anxiety. Recently, Levothyroxine has been used less frequently for fat burning due to possible adverse reactions.
Price for Levothyroxine in pharmacies
The price of Levothyroxine is currently unknown as it is not available for sale.
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!
