Treatment of hypothyroidism. Prevention of relapse after surgical removal of the inert goose. Treatment of the inert will. Replacement and suppressive therapy of malignant thyroid cancer, especially after thyroid removal. Table. 25 μg, 50 μg, 75 μg, 100 μg: helpful in the treatment of hyperthyroidism in combination with antithyroid drugs, after obtaining euthyroidism. Table. 100 μg, 150 μg, 200 μg: suppressive test in the diagnosis of hyperthyroidism.
Synthetic levothyroxine with the same effect as the naturally occurring major hormone secreted by the thyroid gland. After partial conversion to liothyronine (T3), mainly in the liver and kidneys, and after penetration into the cells, it activates T3 receptors, exerting hormone-specific thyroid effects on development, growth and metabolism. After oral administration, fasting is absorbed mainly in the small intestine (up to 80%). Absorption is significantly reduced if the medicine is given with a meal. The maximum plasma concentration is observed 2-3 hours after taking the drug. The onset of action of the drug is observed after 3-5 days. The degree of binding of levothyroxine with specific transport proteins is about 99.97%. Because the binding of the hormone to proteins is not covalent, therefore the bound hormone is constantly and rapidly exchanged with the free hormone fraction. Levothyroxine is degraded mainly in the liver, kidneys, brain and muscles. Metabolites are excreted in urine and faeces. T0,5 levothyroxine is about 7 days, although hyperthyroidism is shorter (3-4 days) and hypothyroidism is longer (about 9-10 days). Due to the high degree of protein binding, levothyroxine is not subject to dialysis or hemoperfusion.
Contraindications:
Hypersensitivity to the active substance or any of the excipients. Untreated hyperthyroidism. Untreated adrenal insufficiency. Untreated pituitary insufficiency. acute myocardial infarction. Acute myocarditis. Acute endocarditis, myocardium and pericardium (pancarditis). The concomitant use of levothyroxine and other antithyroid agents in pregnant women is contraindicated.
Precautions:
Before starting treatment with thyroid hormones, the following diseases should be excluded or treatment should be initiated: ischemic heart disease, angina pectoris, hypertension, hypopituitarism and / or adrenal cortex, autonomic thyroid function. Before performing the suppressive test in the diagnosis of hyperthyroidism, the above conditions should be excluded or treated; the exception is the autonomous function of the thyroid gland, which is not a contraindication to perform the suppressive test. In patients with coronary artery disease, heart failure, cardiac arrhythmias with tachycardia, long-lasting hypothyroidism and in patients with a history of myocardial infarction, even minor drug-induced hyperthyroidism should be strictly avoided. In these patients, the concentration of thyroid hormones should be monitored frequently. In the case of secondary hypothyroidism, it should be determined whether or not adrenocortical insufficiency is accompanied by it. If adrenocortical insufficiency is confirmed, first substitution treatment (hydrocortisone) should be implemented. If there is suspicion of autonomous thyroid function, a TRH test or a scintigraphy of thyroid function tests should be performed. When using sodium levothyroxine in postmenopausal women with an increased risk of osteoporosis, thyroid function should be monitored more often to avoid higher than physiological serum levels of levothyroxine. Substitution therapy with levothyroxine may require an increase in the dose of insulin or other antidiabetic agents. Caution should be exercised in patients with diabetes and diabetes insipidus.Parents of children receiving thyroid hormones should be informed about the possibility of partial baldness during the first few months of therapy; however, this effect is temporary and usually the hair grows back. Caution should be exercised when administering levothyroxine to patients with a history of epilepsy. Occasionally, seizures have been reported after initiation of sodium levothyroxine therapy, which may be the result of thyroid hormone effects on the seizure threshold. Thyroid hormone must not be used to reduce body weight. In patients with normal thyroid function, the usual doses do not cause weight loss. Higher doses may cause serious or even life-threatening side effects such as hypothyroidism and / or impede treatment of hypothyroidism, especially in combination with some weight-reducing agents such as orlistat. This may be due to reduced absorption of Iodine salt and / or levothyroxine.
Pregnancy and lactation:
Treatment with thyroid hormones should be carried out without interruption, especially during pregnancy and breastfeeding. Despite extensive experience in the use of levothyroxine during pregnancy, there is no evidence of a toxic effect on pregnancy or the health of the fetus or newborn baby. The amount of thyroid hormones secreted into breast milk, even when treated with high doses of levothyroxine, is too low to cause the development of thyrotoxicosis or inhibition of secretion of TSH in a child. During pregnancy, the need for levothyroxine may increase due to the increased concentration of estrogen - thyroid function should be monitored during and after pregnancy and the dose of thyroid hormone should be adjusted accordingly. During pregnancy and breastfeeding, no diagnostic tests should be carried out involving thyroid suppression.
Side effects:
Rare: mild intracranial hypertension in children. Not known: headache, flushing, fever and sweating, hypersensitivity reactions (including rash, pruritus and swelling), weight loss, tremor, anxiety, hyperactivity, insomnia, angina pectoris, arrhythmias, palpitations, accelerated activity heart failure, increased blood pressure, heart failure, myocardial infarction, shortness of breath, increased appetite, abdominal pain, nausea, diarrhea, vomiting, muscle cramps, muscle weakness, premature ossification of the cranial sutures in infants and premature obliteration of the epiphyseal ridge in children, irregular menstruation . Intolerance to heat and transient alopecia may occur in children. In case of hypersensitivity to levothyroxine or to any of the excipients, allergic reactions of the skin and respiratory system may occur.
Dosage:
Orally. The dosage recommendations given are only general guidelines. The individual daily dose should be determined based on the results of laboratory tests and clinical trials. In patients with preserved thyroid function, a lower dose of substitution may be sufficient. In elderly patients, patients with ischemic heart disease and patients with severe or long-lasting hypothyroidism, treatment should be started at a low initial dose, which should then be increased slowly at longer intervals, with frequent monitoring of thyroid hormone levels. Experience has shown that lower doses are also sufficient for people with low body weight and those with high nodular goitre. Because the tablets can be divided into halves, the dosage can be started at a dose of 12.5 μg. Since elevated levels of T4 and fT4 are found in some patients, the concentration of TSH in the serum is a better reference for further therapy. In patients using a given dose of levothyroxine, it is recommended that when switching to another formulation, dose adjustment should be appropriate, depending on the patient's clinical response and the results of laboratory tests.Adults. Hypothyroidism: initial dose 25-50 μg daily, maintenance dose 100-200 μg daily (increased by 25-50 μg at intervals of 2-4 weeks). Prevention of relapse will: 75-200 μg daily. Inert urine: 75-200 μg daily. Auxiliary to the treatment of hyperthyroidism in combination with antithyroid drugs: 50-100 μg daily. Therapy in thyroid cancer after thyroid removal surgery: 150-300 μg daily. In thyroid function suppression tests: 100 μg - 2 tabl.(200 μg) daily for 14 days before scintigraphy; Table. 150 μg - 1 tablet (150 μg) daily for 14 days before performing scintigrams; Table. 200 μg - 1 tabl. (200 μg) daily for 14 days before scintigraphy. In the case of hypothyroidism and thyroid removal surgery due to malignant thyroid cancer, the treatment usually lasts throughout life, and in the case of an inert goat and prophylaxis of recurrence, the will lasts for several months or years, or even the end of life; in the case of adjunctive therapy, the duration of treatment depends on the period of antithyroid drug use. In the treatment of the inert goat, treatment lasting from 6 months to 2 years is necessary. If treatment with the preparation does not produce expected results during this period, other treatment options should be considered. In elderly patients in individual cases, eg in the case of coexistence of heart disease, the dose of levothyroxine sodium should be increased more slowly and at the same time regularly monitored for TSH levels. The total daily dose should be taken in the morning, on an empty stomach, at least half an hour before breakfast. The tablets should be swallowed whole, without chewing, with liquid.Children. The maintenance dose is usually 100-150 μg / m2 pc. per day. For newborns and infants with congenital hypothyroidism, in whom fast substitution is important, the recommended starting dose is 10-15 μg / kg bw / day for the first 3 months. Then, the dose should be adjusted individually based on the clinical picture and thyroid hormone values, and TSH. For children with acquired hypothyroidism, the recommended starting dose is 12.5-50 μg / day. The dose should be increased gradually at intervals of 2-4 weeks based on the clinical picture and the values of thyroid hormone and TSH concentrations until the full substitution dose is obtained. Infants should receive the entire daily dose at least half an hour before the first feeding. For this purpose, dissolve the tablet in a small amount of water (10-15 ml) and give the resulting suspension with an additional amount of liquid (5-10 ml). The suspension should be prepared immediately before each serving.
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