Thyrostatic drugs are active substances that intervene inhibitory in the hormone metabolism of the thyroid gland and are mainly used in various forms of hyperthyroidism. In addition to pharmaceutical thyrostatic agents, some herbal or homeopathic substances also exist, but they should be considered therapeutically only in mild hyperthyroidism.
What are thyrostatic agents?
Extracts or extracts of wolfberry have a lowering effect on thyroid hormones. Thyrostatic agents are substances that, by inhibiting the synthesis or secretion of thyroid hormones or the incorporation of iodine into the precursors of thyrohormones, normalize thyroid function and induce remission of clinical symptoms. In general, thyrostatic substances are divided into so-called iodination and iodization inhibitors as well as iodides, which intervene in the hormone metabolism of the thyroid gland in different ways. Thyrostatic agents are generally used in the therapy of various subtypes of hyperthyroidism (hyperthyroidism) such as Graves’ disease, functional thyroid autonomy, and iodine-induced hyperthyroidism.
Medical application, effect, and use
The three different substance groups of thyrostatic drugs develop their effect at different points of attack of the metabolism of the thyroid gland or thyroid hormones and serve to normalize and stabilize thyroid function. Thus, the so-called thiourea derivatives have an inhibitory effect on the peroxidases (iodization inhibitors). These enzymes catalyze the reduction of peroxides, which in turn are required for the incorporation of iodine into thyroid hormones and the binding of the precursors monoiodtyrosine and diiodtyrosine. These thyrostatic drugs are used in particular in Graves’ disease, in the pre- and post-treatment of radioiodine therapy, in the run-up to surgery, and in thyrotoxic crisis. In case of struma formation as well as hypersensitivity reactions (including fever, urticaria) the application of these thyreostatics is contraindicated. Perchlorate (iodination inhibitor), on the other hand, primarily reduces the transport of iodide into the thyroid gland by inhibiting the uptake of iodide into the thyrocytes. Perchlorate has only a narrow therapeutic range and is generally used for rapid iodide blockade of the thyroid gland or prophylactically prior to radiological examinations with iodine-containing contrast media, especially in patients in whom the contrast medium can trigger a thyrotoxic crisis. Iodides reduce hormone secretion in high doses by blocking the enzymes that release thyroid hormones in the blood so that they can no longer be effective. Iodides are applied exclusively preoperatively, usually in combination with thiourea derivatives, or short-term in thyrotoxic crises.
Herbal, natural, and pharmaceutical thyrostatic agents.
Herbal thyrostatic agents primarily include wolfstrap herb (Lycopi herba) or extracts or extracts of Lycopi herba as single or combination therapeutic agents. In particular, the lithospermic acid contained in the leaves of the plant is thought to have a lowering effect on thyroid hormones by inhibiting iodine transport. However, the thyrostatic should only be used in cases of mild hyperthyroidism with nervousness and/or rhythm disturbances (so-called vegetative nervous disorders). In addition, it should be taken into account that preparations containing Lycopi herba may interfere with radioisotopic examinations of the thyroid gland. In addition, Wolfstrappkraut is contraindicated in cases of enlargement of the thyroid gland without functional impairment. As part of homeopathic therapy, in addition to Lycopi herba, Chininum arsenicosum (quinine arsenite), Lycopus virginicus (Virginian wolfbane), Adonis vernalis (Adonis rose), Fucus vesiculosus (colloquially bladderwrack), Kalium iodatum (Schüßler salt No. 15) or Iodum can be applied, especially in cases of mild hyperthyroidism with nervous heart complaints. Common and therapeutically proven chemical-pharmaceutical agents are mainly perchlorate, which as an iodination inhibitor inhibits the absorption of iodide, and the thiourea derivatives thiamazole, carbimazole and propylthiouracil, which as iodination inhibitors reduce the synthesis of thyroid hormones.
Risks and side effects
Thyrostatic therapy interventions can lead to various adverse side effects depending on the dosage. For example, hypersensitivity reactions (drug exanthema) and occasionally joint pain can often be observed at low doses. In particular, high doses lead to marked suppression of the thyroid gland, through which the pituitary gland stimulates TSH secretion to increase hormone secretion and may thus cause hyperplasia. Other side effects of thyrostatic drugs include changes in blood counts (leukopenia, granulocytopenia, or agranulocytosis), goiter (enlargement of the thyroid gland), liver damage, hypothyroidism (underactive thyroid), jaundice, progression of exopthalmos (bulging eyes), and gastrointestinal symptoms. In addition, the use of thyrostatic agents should be avoided during pregnancy, if possible, because they cross the placental barrier, affect the thyroid gland of the growing child, and may lead to hypothyroidism.
