Chemical Properties
White Solid
Usage
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 thyroid hormone, but has been used to treat hyperlipidemia.
Originator
Synthroid,Flint,US,1953
Uses
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 thyroid hormone, but has been used to treat hyperlipidemia.
Definition
ChEBI: The sodium salt of L-thyoxine. It is used as replacement therapy in the treatment of hypothyroidism.
Indications
Levothyroxine sodium (Levothroid, Synthroid, Levoxine)
is the sodium salt of the naturally occurring levorotatory
isomer of T4. It is the preparation of choice for
maintenance of plasma T4 and T3 concentrations for
thyroid hormone replacement therapy in hypothyroid
patients. It is absorbed intact from the gastrointestinal
tract, and its long half-life allows for convenient oncedaily
administration. Since much of the T4 is deiodinated
to T3, it is usually unnecessary to use more expensive
preparations containing both T4 and T3.The aim
is to establish euthyroidism with measured serum concentrations
of T4, T3, and TSH within the normal range.
The TSH-suppressive effects of exogenous T4 also
prove useful in removing the stimulatory effects of TSH
on the thyroid gland in the management of simple
nonendemic goiter, chronic thyroiditis, and TSHdependent
thyroid carcinoma.
Manufacturing Process
A 9.30 g portion of N-acetyl-L-diiodotyrosinamide was suspended in 100 ml of
0.05M boric acid (H3BO3) and 100 ml of 95% ethanol, and the solid was
dissolved by adjusting the pH to 10.5 with 2N sodium hydroxide (NaOH). A
15% (by weight) portion of manganese sulfate monohydrate was added and
the solution heated at 44°C under conditions of oxygenation while being
agitated mechanically. After approximately 24 hours of incubation, the
precipitated product was collected and separated from the catalyst, providing
the amide of N-acetyl-L-thyroxine in 30.6% yield. On hydrolysis (removal of
both amide functions), achieved by refluxing in glacial acetic acid-hydrochloric
acid (approximately 2:1), L-thyroxine is obtained. It was isolated as the
sodium salt, containing approximately 5 molecules of water of hydration.
Brand name
Levo-T (Alara);
Levolet (Vintage); Levothroid (Lloyd); Levoxyl (Jones);
Novothyrox (Genpharm); Synthroid (Abbott); Unithroid
(Stevens J).
Therapeutic Function
Thyroid hormone
General Description
Levothyroxine sodium,O-(4-hydroxy-3,5-diiodophenyl)-3,5-diiodo-2-tyrosinemonosodium salt, hydrate (Synthroid, Letter, Levoxine,Levoid), is the sodium salt of the levo isomer of thyroxine,which is an active physiological principle obtained from thethyroid gland of domesticated animals used for food by humans.It is also prepared synthetically. The salt is a light yellow,tasteless, odorless powder. It is hygroscopic but stablein dry air at room temperature. It is soluble in alkali hydroxides,1:275 in alcohol, and 1:500 in water, to give a pH ofabout 8.9.
Clinical Use
Liothyronine sodium occurs in vivo together withlevothyroxine sodium; it has the same qualitative activitiesas thyroxine but is more active. It is absorbed readily fromthe gastrointestinal tract, is cleared rapidly from the bloodstream,and is bound more loosely to plasma proteins than isthyroxine, probably because of the less acidic phenolic hydroxylgroup.Its uses are the same as those of levothyroxine sodium,including treatment of metabolic insufficiency, male infertility,and certain gynecological disorders.
Veterinary Drugs and Treatments
Levothyroxine sodium is indicated for the treatment of hypothyroidism
in all species.
