Levothyroxine: instructions for use and reviews
Levothyroxine is a hormonal drug used for the diagnosis, treatment and prevention of thyroid diseases.
Release form and composition
https://synthroidnews.net/ is produced in the form of tablets: flat-cylindrical, white or white with a creamy shade of color (10 or 25 pieces in blisters, 1, 2 or 5 packs in a cardboard box).
The composition of 1 tablet includes:
- Active substance: sodium levothyroxine – 25, 50 or 100 mcg;
- Auxiliary components: milk sugar (lactose), talc, Kollidon 25, calcium hydrogen phosphate dihydrate, magnesium stearate.
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. Enhancing tissue oxygen demand, it is a stimulator of 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 contributes to the activation of energy processes, which positively affects the functions of the liver, kidneys, cardiovascular system and central nervous system.
Levothyroxine is involved in metabolic processes in the liver and goes 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 a course of therapy. When Levothyroxine is prescribed to patients with diffuse goiter, a decrease in the size of the thyroid gland is observed in about 3-6 months.
After oral administration, approximately 80% of the dose of levothyroxine is absorbed in the upper small intestine. Absorption of the drug decreases after a meal. The maximum content of a substance in 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 elimination half-life is 6–7 days. Levothyroxine is eliminated through the kidneys and excreted with bile (up to 15% of the administered dose).
Indications for use
- Euthyroid goiter;
- Goiter after removal of the thyroid gland (as a replacement therapy and as prevention);
- Thyroid cancer (after surgical treatment);
- Diffuse toxic goiter: after reaching an euthyroid state against the background of thyrostatic treatment (as monotherapy or simultaneously with other drugs).
Also, the drug is used as a diagnostic tool during the thyroid suppression test.
- Untreated thyrotoxicosis;
- Acute myocarditis, acute myocardial infarction;
- Untreated adrenal insufficiency;
- Hypersensitivity to the drug.
According to the instructions, Levothyroxine should be taken with caution in the presence of cardiovascular diseases: coronary heart disease (atherosclerosis, angina pectoris, a history of myocardial infarction), arrhythmias, and arterial hypertension. Caution should also be exercised when using Levothyroxine in patients with diabetes mellitus, long-term severe hypothyroidism, malabsorption syndrome (dose adjustment may be required).
Therapy for hypothyroidism during pregnancy should continue. Concomitant use with thyreostatics is contraindicated. Nursing women should take the drug with caution under the supervision of a doctor, with strict adherence to the prescribed doses.
Instructions for use
Levothyroxine: the method and dosage of Levothyroxine is taken orally, in the morning on an empty stomach (30 minutes before a meal), washed down with a small amount of liquid (1/2 cup of water). Chew the tablet should not be.
The daily dose of the drug is determined individually based on the evidence.
During the substitution treatment of hypothyroidism in patients under 55 years old without cardiovascular disease, Levothyroxine is prescribed in a daily dose of 1.6-1.8 μg / kg body weight; patients from 55 years old or in the presence of disorders of the cardiovascular system – 0.9 mcg / kg body weight. Calculation of the dose for significant obesity should be done at “ideal weight”.
At the initial stage of replacement therapy for hypothyroidism in patients younger than 55 years old without cardiovascular disease, 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 years, Levothyroxine is prescribed in an initial dose of 25 mcg per day. Before normalizing the level of thyroid-stimulating hormone in the blood 1 time in 2 months, a dose increase of 25 μg is carried out. If cardiac symptoms develop or worsen, cardiac treatment should be corrected.
In the treatment of 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: 100-150 mcg / 4-5 mcg / kg;
- More than 12 years: 100-200 mcg / 2-3 mcg / kg.
For other indications, the following dosage 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 conducting a thyroid suppression test, Levothyroxine is prescribed at 75 mcg per day 4 and 3 weeks before the test, 2 and 1 week at 150-200 mcg per day.
The daily dose of Levothyroxine is given to infants 30 minutes before the first feeding in one go. The tablet should be dissolved in water to a state of fine suspension (prepared immediately before use).
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 the maintenance dose is carried out at longer time intervals – every 2 weeks by 12.5 mcg per day. Such patients need to more often determine the level of thyroid-stimulating hormone in the blood.
With hypothyroidism, levothyroxine is usually taken throughout life. With 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.
With the correct use of Levothyroxine, side effects, as a rule, do not develop.
In the case of hypersensitivity to the components of the drug, allergic reactions can occur.
In case of an overdose, a thyrotoxic crisis is observed, manifested by symptoms such as hyperhidrosis, tachycardia, weight loss, exophthalmos, finger tremor. In this case, it is necessary to reduce the dose of the drug. In case of acute intoxication, plasmapheresis and gastric lavage are recommended. The appointment of glucocorticosteroids, colestyramine, cardiac glycosides, beta-blockers and oxygen therapy are also allowed. Antithyroid drugs are contraindicated.
With hypothyroidism due to damage to the pituitary gland, it should be ascertained whether adrenal cortex insufficiency is associated with the disease. In this case, in order to avoid the development of acute adrenal insufficiency, replacement therapy with glucocorticosteroids must be started before the start of therapy for hypothyroidism with thyroid hormones.
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 thyreostatic drugs is contraindicated, since it increases the risk of hypothyroidism in the fetus.
Use in old age
In elderly patients suffering from hypothyroidism for a long time, it is recommended to start treatment with the drug gradually.
With the simultaneous use of Levothyroxine with some drugs, the following effects may occur:
Indirect anticoagulants: enhancing their action (may require a decrease in their dose);
Tricyclic antidepressants: enhancing their action;
Estrogen-containing drugs: an increase in the content of thyroxin-binding globulin (an increase in the dose of sodium levothyroxine may be required);
Insulin, oral hypoglycemic drugs: increased need for them;
Cardiac glycosides: decrease in their effect;
Colestyramine, colestipol, aluminum hydroxide: a 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 not associated with blood plasma proteins;
Somatotropin: acceleration of the closure of epiphyseal growth zones;
Phenobarbital, carbamazepine, rifampicin: increased clearance of sodium levothyroxine (may require an increase in its dose).
Analogues of Levothyroxine are: Eutirox, Bagothyrox, L-thyroxine.
Terms and conditions of storage
Store in a dry, dry place out of the reach of children at temperatures up to 25 ° C.
Shelf life is 2 years.
Pharmacy Vacation Terms
It is released without a prescription.
Reviews about Levothyroxine, which are left by experts, suggest that treatment should be carried out, necessarily controlling 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. The metabolic status is best restored gradually, starting with the minimum doses. Most patients have to take Levothyroxine all their lives, since hypothyroidism cannot be completely cured. Patients report that improvement occurs within a few weeks, and the maximum effect is achieved 3-6 months after the start of therapy.
Patients claim that the drug is well tolerated and, with the right 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 tremor, angina pectoris, arrhythmias, tachycardia. If we compare Levothyroxine and its analogue Eutiroks (manufactured in Germany), then with an identical active substance and the same effect on the body, the latter is characterized by 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 during bodybuilding, as it stimulates the central nervous system, increases working capacity, promotes fat burning, and intensifies heat production and metabolic processes. Its effectiveness is greater than that of most fat burners. It is noted that it is preferable to use it for such purposes than triiodothyronine. However, occasionally taking the drug does not produce results, especially if the patient adheres to a low-carb 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 μg, 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. In case of pain in the heart, heart palpitations, anxiety and restlessness, riboxin, aspartame and beta-blockers are prescribed. Recently, Levothyroxine is used to burn fat less often due to possible adverse reactions.