Thyroxine

• L-( -)- thyroxine
• (S)- thyroxine
• Tetraiodothyronine
• 3,3 ', 5,5'- Tetraiod - L - thyronine
• 2-amino- 3-[ 4 - (4 -hydroxy-3 ,5- diiodphenoxy ) - 3,5- diiodphenyl ] propanoic acid

• C15H11I4NO4 ( levothyroxine )
• C15H10I4NNaO4 ( levothyroxine sodium salt)

• 51-48-9 ( levothyroxine )
• 55-03-8 ( levothyroxine sodium salt)

H03AA01

231-233 ° C ( levothyroxine )

Slightly soluble in water (0.105 mg · l-1 at 25 ° C)

• 20 mg · kg -1 ( LD50 rat, ip, levothyroxine sodium salt)
• 50 mg · kg -1 ( LD50, rat sc, levothyroxine sodium salt)

Template: Infobox chemical / molecular formula search available

Thyroxine (T4, 3,3 ', 5,5' -L- thyronine - Tetraiod, θυρεοειδής of gr, thyreoeides, shield -like ') is a hormone that is produced in the thyroid gland in mammals.

Thyroxine is a non-proteinogenic α - amino acid with the chemical formula C15H11I4NO4. Thyroxine is the prohormone to triiodothyronine, T3 short ( three iodine atoms in the molecule). These thyroid hormones are essential for energy metabolism and important partner for many other hormones such as insulin, glucagon, somatotropic hormone and adrenaline. The overriding rule is the hormone thyroid-stimulating hormone ( TSH).

History, isolation and synthesis

Edward Calvin Kendall isolated in 1919 for the first time thyroxine from dried thyroid preparations. Charles Robert Harington characterized and synthesized it for the first time 1926. During the same year thyroxine was by Georg Friedrich Henning for the treatment of thyroid suffering under the name " Thyroxin Henning " placed on the market.

Chemical Properties

The thyroxine molecule contains four iodine atoms ( tetraiodothyronine ), hence also known as T4. Thyroxine has the body - bound to thyroxine-binding globulin, - a half-life of approximately eight days.

Therapeutic Application

Thyroxine is used to treat underactive thyroid (hypothyroidism). People with this disease need lifelong hormone replacement usually. Here thyroxine is taken as a tablet sober for at least 30 minutes before breakfast, to maximize the absorption of poorly absorbable tend hormone in the intestine. The dose is usually within a range between 12.5 micrograms and 200 micrograms per day. For the treatment of severe hypothyroid coma, there is also an intravenous form of thyroxine.

In addition to its use in hypothyroidism can thyroxine in addition a sufficient supply of iodine for the treatment of goiter ( goiter) use. In hyperthyroidism, the administration of thyroxine is contraindicated, except in special, rarely used treatment strategies ( block and replace).

Thyroxine is improperly used as a slimming pill. For this indication, there is neither an approval nor an evidence of efficacy. Although administration of thyroid hormone may increase energy expenditure, but this can be compensated by an increased food intake. In addition, thyroid hormones favor of overdose insulin resistance, the cardiovascular system is more stressed, especially in women after menopause increases the risk of osteoporosis. Deaths due to overdose are known.

Thyroxine and triiodothyronine also have a role in the effect of gain and phase prophylaxis for the treatment of depression.

At a daily intake of thyroxine or thyrotropin - thyronine the value ( TSH) should be monitored regularly. This is particularly true in the setting phase and following dose changes.

Thyroxinpräparate different manufacturers can differ significantly in their bioavailability, which is why a change in the commercial preparation is not recommended if the previous preparation is tolerated.

Extensive studies on pharmacoepidemiology of Thyroxinpräparaten were presented by the Robert Koch Institute.