DL-Thyroxin Chemische Eigenschaften,Einsatz,Produktion Methoden
R-Sätze Betriebsanweisung:
R40:Verdacht auf krebserzeugende Wirkung.
S-Sätze Betriebsanweisung:
S22:Staub nicht einatmen.
S24/25:Berührung mit den Augen und der Haut vermeiden.
S36:DE: Bei der Arbeit geeignete Schutzkleidung tragen.
Beschreibung
L-Thyroxine is a synthetic form of the thyroid hormone thyroxine.
In vivo, L-thyroxine (0.9 and 2.7 μg) inhibits synthesis and release of thyrotropin induced by thyrotropin-releasing hormone from the anterior pituitary in mice. It also reverses decreases in levels of circulating thymic serum factor (FTS) and the number of T rosette-forming cells in an old age-induced mouse model of hypothyroidism. Formulations containing L-thyroxine have been used in the treatment of hypothyroidism.
Chemische Eigenschaften
Crystalline Solid
Verwenden
One of the thyroid hormones involved in the maintenance of metabolic homeostasis. Synthesized and stored as amino acid residues of thyroglobulin, the major protein component of the thyroid follicular
colloid. Synthesis and secretion are regulated by the pituitary hormone (TSH). Deiodinated in peripheral tissues to the active metabolite, liothyronine. The D-form has very little activity as a thyroi
d hormone, but has been used to treat hyperlipidemia.
Definition
ChEBI: The L-enantiomer of thyroxine.
Indications
Effects of this drug depend heavily on dosage. In small doses, levothyroxine exhibits anabolic
action. In medium doses, it stimulates growth and development of tissue, metabolism
of protein, fats, and carbohydrates, increases functional activity of central nervous and cardiovascular
systems, as well as kidneys and liver. In large doses, it slows the thyrotropic
activity of the hypophysis and suppresses thyroid gland production. Levothyroxine is used
for hypothyroidism, myxedema, thyrotoxicosis, erythyroid conditions, and cretinism.
Pharmakokinetik
Because of its firmer binding to carrier proteins, synthetic crystalline L-T4 sodium salt (levothyroxine
sodium, Synthtoid, Euthyrox) has a slower onset of action than crystalline T3 or a desiccated thyroid
preparation. Its administration leads to a greater increase in serum T4 but a lesser increase in serum T3
than compared with Thyroid USP. The availability of 11 different tablet strengths, ranging from 25 to
300 μg, allows individual dosing
läuterung methode
Purification is the same as for the D-isomer above. Likely impurities are tyrosine, iodotyrosine, iodothyroxines and iodide. Dissolve it in dilute ammonia at room temperature, then crystallise it by adding di[] 546 +27.8o (c 5, EtOH). [Harrington et al. Biochem J 39 164 1945, Nahm & Siedel Chem Ber 96 1 1963, Reineke & Turner J Biol Chem 161 613 1945, Chalmers et al. J Chem Soc 3424 1949, Beilstein 14 II 378, 14 III 1566, 14 IV 2373.]
DL-Thyroxin Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
