Thyroid

Antithyroid drugs: classification, names

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I

Antitireaboutgood wededstva (Greek anti- against + anat. [glandula] thyreoidea thyroid, synonym: thyrostatic agents, thyrostatics)

Drugs used to inhibit the synthesis of thyroid hormones are used for the conservative treatment of hyperthyroidism, the preoperative preparation of patients with diffuse toxic goiter with the aim of eliminating the clinical manifestations of thyrotoxicosis. Some A. s. have an immunosuppressive effect, the mechanism of which is not well understood.

A. p. are substances of different chemical nature. Large group A. s. is a derivative of thiourea (Nd NJ CS and contains in its molecule or imidazole grouping (mercazole and its foreign counterparts - tiamazol, carbimazole, methimazole, etc.) or pyrimidine core (methylthiouracil, propylthiouracil). As A. s. also use some inorganic iodine compounds, iodine-131 radionuclide (131 I), potassium perchlorate and lithium carbonate. The most widely used A. are the domestic mercazole and its foreign analogues, the pharmacokinetics of these drugs are similar.

Mercazolil (Mercazolilum, synonym: Thiamazolum, Antiroid, Mereazole, Methimazole, etc.) is 1-methyl-2-mercapto-midazole. It is highly soluble in water, easily absorbed in the gastrointestinal tract, appears in the blood after 20 min after administration, the maximum concentration of the drug in the blood is determined after 2 h after taking. Since Mercazolyl selectively accumulates in the thyroid gland (Thyroid gland), its concentration in the blood gradually decreases over the next 8 h. Sulfur, which is a part of mercazolyl, inhibits the activity of specific oxidases localized in the follicles of the thyroid gland and, in the end, inhibits thyroglobulin iodization and the synthesis of thyroid hormones (thyroid hormones) in the thyroid gland.

Indications for use mercazole is diffuse toxic goiter (see diffuse toxic goiter). In non-severe goiter without a significant increase in gland, mercazole is the only treatment for 1 1 /2- 2 years. During the preoperative preparation of patients with diffuse toxic goiter of large sizes and with severe thyrotoxicosis or during the preparation of patients for treatment with iodine radionuclide, as well as mixed toxic goiter and toxic adenoma are also prescribed mercazolil.

Before starting treatment with mercazole (or its foreign counterparts) it is necessary to perform a complete blood count. The number of leukocytes is less than 3.0․10 9 /l and the absolute number of segmented leukocytes is less than 2.0․10 9 /l serve as an absolute contraindication to the appointment of Mercazolyl and its analogues.

The daily dose of the drug is 0.03-0.04 g, in some cases, it can be increased to 0.06-0.08 year The need for a blocking dose of mercazole in pregnancy decreases to 0.01–0.015 g per day, this dose does not affect the development of the fetus and the embryogenesis of the thyroid gland. After birth, the need for the drug increases again. Breastfeeding while taking merkazolila should be discontinued, because its concentration in breast milk is equal to its concentration in the blood.

The drug is taken after eating, the dose is distributed evenly throughout the day, the intervals between doses of the drug should be no more than 8 h. General treatment regimens mercazole does not exist. The dose of mercazole is selected individually according to the clinical picture of the disease. With a decrease in tachycardia, an increase in body weight, and a better sense of well-being, the dose is reduced by 0.005-0.01. g per day. A faster dose reduction can lead to a relapse of the disease. Maintenance dose is 0.01-0.015 g per day. When combined with diffuse toxic goiter with endocrine ophthalmopathy and a pronounced goiter effect of the drug, that is, a progressive increase in the gland during the use of mercasolil, its reception is combined with the administration of thyroid hormone preparations, which avoids the signs of drug hypothyroidism, aggravating ophthalmopathy. The daily dose of thyroid hormone drugs in combination with mercazolil is 5-10 mcg triiodothyronine (or the corresponding amount of other thyroid hormone drugs). Such a combination allows the fuller utilization of the immunosuppressive effect of mercazolil and is more therapeutically beneficial than a simple reduction in its dose. A blood test for treatment with mercazole must be done every 10-14 days. Before the end of treatment with mercazole, it is recommended to test with thyroliberin and determine the titre of thyroid-stimulating antibodies in the patient: the absence of these antibodies in the blood and an adequate response of the thyroid gland to the administration of thyroliberin are progiostically favorable signs.

Contraindications to the appointment of Mercazolil, in addition to the initial leukopenia of any origin, are individual hypersensitivity to the drug, which is expressed in the appearance of urticaria, arthralgia, the development of segmented leukopenia and thrombocytopenia. A relative contraindication to the appointment of Mercazolyl is pregnancy. With a sufficiently high concentration in the blood, mercazole can block the oxidation processes not only in the thyroid gland, but also in other tissues and primarily in the bone marrow, causing leukopenia. In such cases, treatment with mercazole is stopped and agents that stimulate leukogenesis are prescribed: pentoxyl, leucogen, and sodium nucleinate. In severe cases, blood transfusions are used. It is not recommended to combine the use of mercazole and drugs that can cause leukopenia - amidopirin, sulfonamides, etc.

Release form of mercazole: tablets of 0.005 year Storage: B.'s list in a dry, dark place.

Iodine preparations as independent A. s. do not apply. They are used in complex preoperative preparation of patients with diffuse toxic goiter to reduce bleeding during surgery. It was assumed that the mechanism of thyreostatic action of iodine is mediated through the pituitary gland, by inhibiting the synthesis of thyroid-stimulating hormone (TSH). However, it is more likely that the specific effect of iodine on the cytoplasmic membranes of the cells of the glandular epithelium of the thyroid gland and the decrease under the influence of iodine of the role of a universal modulator — cyclic 3 1, 5 1 -AMP in stimulating the thyroid gland of TSH, is considered. Iodine preparations have a clear dose-dependent effect. When the thyroid gland is saturated with iodine, its suppressing thyreostatic action is replaced by a stimulating one, the so-called iodine-based develops.

Applied iodine in the form of a 5% alcohol tincture, 5 drops added in 1 /2 cups of milk and take 2 times a day. Since iodine has a cumulative effect, a 7–10-day break should be taken after 20 days of administration to prevent signs of iodism.

Tablets "Antistrum" (Tabulettae "Antistruminum") contain 0,001 g potassium iodide. In diffuse toxic goiter, the initial dose is 0.002–0.003. g, maintenance dose in combination with mercazolyl is 0.001-0.002 g a day, 2–3 times a week, take the medicine tablets with milk, the therapeutic effect occurs in 15–20 days. Product: in bottles of 50 and 100 tablets. Storage: in a dry, dark place.

A side effect of all inorganic iodine compounds used as A. s. May be allergic reactions, iodism phenomena (runny nose, drooling, urticaria, Quincke edema, etc.). In these cases, iodine preparations are canceled, prescribe antihistamines and other anti-allergic drugs.

Radionuclide 131 I is the only one out of all radionuclides. Iodine is used for therapeutic purposes, treatment is carried out in specialized hospitals. Radionuclide 131 I is given to patients in mixture with sodium iodide solution.

The dose is calculated individually, based on the size of the thyroid gland and the activity of its absorption 131 I. Absorption from the gastrointestinal tract begins after 20 min and ends after 3 h after taking the drug. The full effect of 131 I manifests itself in 2–3 months. Iodine radionuclide is administered once (the entire dose) and fractionally (2-4 each). MCI).

Indications for use 131 I as A. with. are diffuse toxic goiter in the elderly, especially relapses of the disease after subtotal resection of the thyroid gland, allergy to other A. s., differentiated forms of thyroid cancer that can absorb 131 I. Contraindications are the young age of patients, leukopenia, severe damage to the liver and kidneys. accompanied by the oppression of their function. Iodine treatment with radionuclide can cause the development of post-radiation thyroiditis (thyroiditis), transient thyrotoxicosis (due to the destruction of thyroid follicles), leukopenia, hypothyroidism.

Potassium Perchlorate as A. with. practically not used, but in exceptional cases (the absence of other A. s. or their intolerance), it can be used mainly during the preparation of patients with diffuse toxic goiter for surgery. Potassium perchlorate blocks iodotyrosine deiodase and iodine fixation in the thyroid gland. The drug is taken fractional doses of 0.2—0.4 g (depending on the severity of thyrotoxicosis) every 8 h. The effect of treatment does not come immediately (after 8-13 weeks).

Lithium carbonate (Lithii carbonas, a synonym for Lithium carbonicum) has sedative and thyrostatic properties, the latter is associated with blocking the release of iodine in the thyroid gland and the transformation of T4 in t3 in blood. The use of the drug in practice is limited due to the small difference between the effective and toxic dose. This makes it necessary to continuously determine the concentration of lithium in the blood. Its maximum blood concentration is 1.5 mEq / l, upon its achievement, treatment is stopped. The highest lithium concentration in the blood is in the range between 1 and 3 h after taking the pill. The effect of treatment occurs in 10-14 days. Daily dose of 0.3-0.9 g (depending on the severity of thyrotoxicosis). With an overdose, signs of lithium intoxication appear: thirst, dyspepsia, loss of appetite, muscle weakness. It must be remembered that there is no specific antidote for lithium. Contraindications to therapy with lithium are kidney and cardiovascular diseases, as well as pregnancy.

Form release: coated tablets, 0.3. g (in a package of 100 tablets). Storage: in a dry place.

Bibliography: Hormone therapy, ed. X. Shambaha and others, trans. with him., M., 1988, Potemkin V.V. Endocrinology, M., 1986, N.T. Starkova Clinical endocrinology, p. 119, M., 1983.

II

Antitireaboutgood wededstva (antithyreoidea, anti- + anat. glandula thyreoidea thyroid gland, syn. thyreostatics)

drugs that inhibit the synthesis of thyroid hormones and used for its hyperfunction (mercazole, potassium perchlorate, potassium iodide, etc.).

Thyroid problems

The thyroid gland is a word familiar to everyone, and many even know where it is located - in the lower parts of the larynx. But what is its role for the human body? The thyroid gland enters the complex endocrine system, which is responsible for all the processes occurring in the body. Thyroid gland, in particular, produces two major hormones - thyroxin and triiodothyronine, involved in metabolic processes, in the growth and development of tissues and organs. Also thyroid cells produce thyrocoeltonin - a hormone responsible for phosphorus-calcium metabolism, and therefore, for the state of human bones, teeth.

Waste activity

It would seem that once the thyroid gland produces such significant hormones, the more active it is, the better it should be, all processes will go faster and stronger. But in fact, this is not the case at all. Nature laid the balance of everything in it, and the human endocrine system in particular. If the thyroid gland works too actively, then it badly affects the state of the body, however, the lack of thyroid hormone production is also fraught with many problems. Active thyroid gland causes hyperthyroidism or thyrotoxicosis.

What does antithyroid mean?

If the thyroid gland is too active, then antithyroid drugs help to combat this. From the name of these medicines it is clear that they work against - against the thyroid gland. Such funds are also called thyrostatics. Medical preparations included in the group of antithyroid drugs can normalize the activity of the thyroid gland, reducing its activity, and thus reducing the production of thyroid hormones.

Classification of antithyroid drugs

Medicinal products that help combat the over-activity of the thyroid gland are called antithyroid drugs. Their classification is accepted all over the world and contains three groups of agents that serve as antagonists of thyroid hormones:

  • drugs that contribute to the violation of the production of active iodine in the thyroid gland itself,
  • drugs that reduce iodine uptake by thyroid epithelial cells,
  • drugs that destroy iodine in the thyroid gland.

All drugs have a different chemical structure, and the mode of action of the drug depends on it.

Iodine as a medicine

Thyroid hormones are synthesized by epithelial thyroid cells that capture iodine. If this substance is added to the human body, then the thyroid hormone biosynthesis decreases. There is also a violation of the ability of the gland to absorb iodine in the blood. Pharmaceuticals offers two types of iodine preparations that are involved in reducing the activity of the thyroid gland:

  • inorganic iodine - as a chemical natural element,
  • organic iodine as synthesized diiodotyrosine - a component of thyroglobulin - a specific protein of the thyroid gland itself.

The drug of organic origin has antithyroid property, which is actively used mainly in the preoperative period of patients with diffuse goiter, as well as to prevent complications in the postoperative period. Many of these drugs contain the active active ingredient levothyroxine sodium. Inorganic iodine is prescribed not only for the treatment of thyroid hyperactivity, but also as a prophylactic agent. Despite the apparent safety, and nitrile drugs with iodine, however, just like any other drugs, should be taken only on prescription.

Thiourea, its derivatives and hyperthyroidism

Drugs that help reduce the excessive productivity of the thyroid gland, the so-called antithyroid drugs, can be divided into two types - natural, natural, substances such as iodine, and synthetic means obtained from chemical synthesis processes. The latter include thiourea and its derivatives - propylthiouracil, 1-methyl-2-mercaptoimidazole, 2-carboethoximercapto-1-methylimidazole, 6-methylthiouracil. Synthetic antithyroid drug based on thiourea derivatives reduces the iodine metabolism in the thyroid by reducing the iodine metabolism in the thyroid gland itself.

What drugs help with hyperactivity of the thyroid gland?

Thiourea derivatives and iodine are part of the sought-after medicines used as antithyroid drugs. What synthetic drug has antithyroid property? The names of these funds are different, but the main active ingredients are:

  • tiamazol
  • propylthiouracil.

Tiamazol reduces iodine metabolic processes in the thyroid gland, thereby reducing its activity. This chemical is the basis of such drugs as Mercazolil, Tyrosol, Tiamsol, Metizol.

Propylthiouracil inhibits the transformation of iodine in the thyroid gland, thereby causing its relationship to a group called antithyroid drugs. Propylthiouracil-based drugs are most often prescribed for use in Western European countries. In our country, the only propylthiouracil-based drug, Propitsil, is sold in the pharmacy chain.

Since drugs for the treatment of hyperthyroidism and thyrotoxicosis have numerous side effects in relation to the cardiovascular, nervous system, as well as the liver, concomitant medications are prescribed in combination with these drugs.

In the treatment of certain diseases of the thyroid gland, radioactive iodine is used, which, when it enters the patient's body, is captured by the thyroid cells and has a destructive effect on it, reducing the activity and increased hormone production. This preparation gives the greatest positive result only after complete removal of the thyroid gland - thyroidectomy, since the radioactive particles finally destroy the remaining cells of the organ. However, many patients with hyperactivity of the thyroid gland are prescribed preparations of radioactive iodine to normalize the condition.

Only for the intended purpose!

Diseases of the thyroid gland are determined only by a complex of diagnostic methods - analyzes, ultrasound, MRI or CT. Поставить диагноз болезни щитовидной железы только на сборе анамнеза и со слов больного нельзя! Но когда проблема выявлена, грамотный врач может назначить правильное лекарственное средство с учетом всех конкретных факторов.All drugs for the treatment of hyperthyroidism and thyrotoxicosis, caused by increased productivity of the thyroid gland, have numerous side effects and features of use. For example, the opposite effect may occur when a drug that helps reduce iodine uptake by thyroid tissues, after some time becomes a catalyst for its activity to produce the missing amount of hormones. The disease is back. Treatment of hyperthyroidism and thyrotoxicosis is always individual. When an accurate diagnosis is made, in no case can one self-medicate. Only an adequately selected therapy will allow to exclude surgery and lifelong use of special hormonal agents.

Antithyroid drugs are not honorable exhibits of pharmacy windows, but they are the most important means in preserving the health and even the lives of numerous patients with thyroid hyperactivity.

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