Lyotyronin (Liothyroninum)

Pharmacodynamics Pharmacokinetics Indications Carefully Contraindications Dosing and Administration Side effects
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Clinical and pharmacological group: & nbsp

Thyroid hormones, their analogs and antagonists (including antithyroid drugs)

Included in the formulation
АТХ:

H.03.A.A   Thyroid hormones

H.03.A.A.02   Sodium Lithiotonin

Pharmacodynamics:

The left-handed isomer of triiodothyronine (T3): the mechanism of action is not completely clear; affects metabolism, growth and development, especially the development of the central nervous system in children; by the feedback mechanism affects the hypothalamus, the anterior pituitary gland and the thyroid gland, which regulate the concentration of circulating thyroid hormones.

Pharmacokinetics:

Absorption - 95% for 4 hours (may decrease with chronic heart failure, malabsorption, diarrhea). The connection with plasma proteins is more than 99%, unstable. Half-life - 1 day (with euthyroidism), 1.4 days (with hypothyroidism), 0.6 days (with hyperthyroidism). Elimination with feces (15% unchanged and as conjugates).

Indications:

Hypothyroidism of any origin. Treatment of hyperplasia of the thyroid gland: benign goiter with normal function, prevention of recurrence of goiter after surgery or after treatment with radioactive iodine. As a part of combined therapy of toxic goiter with thyreostatic agents (after achieving medical compensation of metabolic processes).

ICD-10

IV.E00-E07.E01   Diseases of the thyroid gland associated with iodine deficiency, and similar conditions

IV.E00-E07.E03.9   Hypothyroidism, unspecified

IV.E00-E07.E04.9   Non-toxic goiter, unspecified

IV.E00-E07.E05.9   Thyrotoxicosis, unspecified

Contraindications:

Hypersensitivity, hyperthyroidism (exception: as a part of combined therapy with thyreostatic treatment of thyroid hyperfunction after reaching the normal state of metabolism), coronary heart disease, myocardial infarction, angina pectoris, acute myocarditis, untreated adrenal insufficiency, diabetes mellitus, Addison's disease, cachexia.

Carefully:

With care given to elderly patients, patients with lesions of the coronary vessels (coronary heart disease), heart failure, and in certain forms of cardiac arrhythmia (tachyarrhythmia).

Pregnancy and lactation:

In a limited amount, it penetrates through the placenta, but extensive clinical experience indicates that there is no adverse effect on the fetus with adequate application. It is important to monitor the dose given to the mother, since the body's need may change during pregnancy.In minimal amounts excreted by breast milk, however, negative impact on the child with adequate application is not documented.

FDA recommendation category A.

Dosing and Administration:

Inside, 30 minutes before eating. The initial dose for adults is 0.5 tablets per day (corresponding to 25 μg of lyotyronine). This dose is advisable to increase every 2-4 weeks by 0.5-1 tablet. Usually the average maintenance dose is from 1 to 1.5 tablets.

Side effects:

From the cardiovascular system: progression of heart failure and angina pectoris.

From the nervous system: pseudotumor brain.

Dermatological: Partial or total hair loss in children is possible during the first few months of therapy; usually normal hair growth is restored later, despite the continuation of therapy.

Hypersensitivity: skin rashes.

Carcinogenicity / mutagenicity: no studies have been conducted; reports of induction of breast cancer are not confirmed; the elimination of thyroid hormones in this state is not required.

Other: hyperthyroidism or overdose, hypothyroidism or insufficient dosage.

In newborns, an overdose can lead to craniostenosis.

Overdose:

Symptoms: Changes in the appetite, changes in the menstrual cycle, chest pain, diarrhea, frequent or irregular heartbeat, fever, tremor, headache, irritability, convulsive tightening of the shins, nervousness, heat intolerance, difficulty breathing, sweating, sleep disorders, vomiting, weight loss , manifestations of thyrotoxic crisis (confusion, fever, jaundice, sudden change of mood, decrease in muscle strength, psychosis, pronounced fatigue, severe weakness - with massive overdose).

Depending on the severity of symptoms, a doctor may recommend a reduction 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 initiated with caution from a lower dose.

Interaction:

β-Adrenoblockers - it is possible to reduce the peripheral conversion of thyroxin to triiodothyronine.

Anabolic steroid, asparaginase, furosemide, salicylates, tamoxifen - possible pharmacokinetic interaction at the level of binding with protein in parallel application; when combined with salicylates, furosemide (in high doses), clofibrate increases the concentration of levothyroxine in the blood.

Anticoagulants, coumarin or indanedione derivatives - it is possible to change the anticoagulant effect depending on the state of thyroid function; an increase in the thyroid hormone dose may require a reduction in the dose of oral anticoagulants.

Tricyclic antidepressants - it is possible to intensify the therapeutic and toxic effects (proarrhythmogenic and CNS stimulation) of both agents in parallel, probably due to an increase in receptor sensitivity to catecholamines; possibly an earlier onset of action of tricyclic antidepressants.

Glycosides of digitalis - may increase the risk of digitalis intoxication with hypothyroidism; substitution therapy with thyroid hormones increases the metabolic rate and may require an increase in the dose of glycoside.

Inductors of cytochrome P450 [barbiturates, especially phenobarbital, griseofulvin, carbamazepine, nevirapine, oxcarbazepine, primidon, rifabutin, St. John's wort of perforated grass, phenylbutazone (mixed inhibitory and inductive effect), phenytoin and, possibly, other hydantoins, ethanol (with chronic use), efavirenz] - increase the splitting of levothyroxine in the liver, which can lead to an increase in the need for it; may need to adjust its dose; phenytoin also reduces the association of levothyroxine with plasma proteins, the concentration of total and free thyroxine in the blood plasma by 15-25%, but the majority of patients remain euthyroid and do not require correction of the thyroid hormone dose.

Special instructions:

Thyroid hormones are not indicated for the correction of vagal symptoms (dry skin, fatigue, constipation, reproductive failure, growth retardation, or obesity) without laboratory confirmation of hypothyroidism, since they can lead to hyperthyroidism in euthyroid patients.

Individual dosage correction is required for each patient according to the clinical response and thyroid function tests.

Treatment with thyroid hormones usually begin with small doses, gradually increasing them to achieve an euthyroid state, with the subsequent administration of maintenance doses.However, this is not required in newborns, for whom the rapid achievement of euthyroidism is important; treatment in them can be started with a full replacement dose. Reduction in the incidence of side effects (eg, hyperactivity) in older children is achieved by starting therapy with a dose corresponding to ¼ of the normal replacement dose, and gradually increasing it by 25% at intervals of 1 week until a complete replacement dose is achieved.

The risk of a rapid dose increase at a younger age is lower than in elderly patients.

In hypothyroid patients with insufficiency of the adrenal cortex or panhypopituitarism, the appointment of replacement therapy with thyroid hormones should be preceded by a correction of adrenocortical insufficiency due to the possibility of developing an acute adrenal cortex deficiency in accelerating metabolism. Supportive therapy with glucocorticoids may also be necessary for prolonged or severe hypothyroidism, including myxedema.

In hypothyroid patients with myxedema or in patients suffering from cardiovascular disease, the initial dose of thyroid hormones should be very small and increase gradually because of the possibility of induction of angina pectoris, coronary artery occlusion or stroke.With the development of cardiovascular reactions, a dose reduction of thyroid hormones.

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