Chemical Properties
white to beige powder
Originator
Cytomel,SKF,US,1956
Uses
One of the hormones produced by the thyroid gland that is involved in the maintenance of metabolic homeostasis. Also produced in peripheral tissues as the active metabolite of Thyroxine.
Uses
L-3,3',5-Triiodothyronine, Sodium Salt is shown to stimulate respiratory activity at the mitochondrial level. T3 is a thyroid hormone that increases rates of proteins synthesis, stimulates the breakdown of cholesterol, and effects embryonic development. In cell culture, T3 regulates cell differentiation and protein expression.
Indications
Liothyronine sodium (Cytomel) is the sodium salt of the naturally occurring levorotatory isomer of T3. Liothyronine is generally not used for maintenance thyroid hormone replacement therapy because of its short plasma half-life and duration of action. The use of T3alone is recommended only in special situations, such as in the initial therapy of myxedema and myxedema coma and the short-term suppression of TSH in patients undergoing surgery for thyroid cancer. The use of T3 alone may also be useful in patients with the rare condition of 5'-deiodinase deficiency who cannot convert T4 to T3.
Definition
ChEBI: Liothyronine sodium is the sodium salt of liothyronine. Thought to be more active than levothyroxine and with a rapid (few hours) onset and short duration of action, liothyronine sodium is used in the treatment of hypothyroidism, particularly in cases of hypothyroid coma. It contains a 3,3',5-triiodo-L-thyroninate.
Manufacturing Process
The 3,5-diiodo compound used as a starting material is a known material and
may be prepared by the method in British Patents 643,089 and 671,070 and
in the Journal of the Chemical Society, London, 1949, page 3424.
Synthesis: L-diiodo thyronine (1.05 g) is dissolved in ammonia (specific
gravity 0.880) (40 ml) and methanol (40 ml) and iodinated slowly with
shaking with N-iodine in KI solution at room temperature. After iodination,most of the ammonia and methanol are removed by evaporation under
diminished pressure, water is added to the original volume, the solution is
heated to 60°C and brought to pH 4 with hydrochloric acid. A crystalline
precipitate is obtained which after cooling to room temperature is collected
and washed with water. At this stage, the crude triiodo thyronine is
contaminated with thyroxine and a little unchanged diiodo thyronine.
Purification: The crude precipitate is dissolved in boiling 2N HCl (300 ml) and
filtered from the relatively insoluble thyroxine hydrochloride. The hot filtrate is
brought to pH 4 with 5N NaOH and triiodo thyronine again separates; after
chilling at 0° to 4°C it is collected, washed with water and dried. The yield of
triiodo thyronine is 70 to 75% of the theoretical. This triiodo thyronine still
contains some thyroxine (about 10%).
The final purification consists of chromatographic separation of thyroxine and
triiodo thyronine on a kieselguhr column using 20% chloroform in n-butanol
equilibrated with 0.5N NaOH as the developing solvent. 80 to 100 mg triiodo
thyronine is purified during each run on a 50 g kieselguhr column. Pure Ltriiodo thyronine has MP 236° to 237°C (dec.) and [α]D29.5° = +21.5 in a
4.75% solution in a mixture of 1 part of N HCl and 2 parts of ethanol.
Liothyronine is commonly used as the sodium salt.
brand name
Thyroid hormone Cytomel (King); Triostat (Jones).
General Description
3,3′,5′-Triiodo-L-thyronine (T
3) is an endocrine hormone produced by the thyroid gland and is regarded as an active thyroid hormone at cellular level. Thyroxine (T
4) serves as a precursor for T
3 and is generated in extrathyroidal tissues.
Biochem/physiol Actions
3,3′,5′-Triiodo-L-thyronine (T3) is a thyroid hormone that increases rates of proteins synthesis, stimulates the breakdown of cholesterol, and effects embryonic development. In cell culture, T3 regulates cell differentiation and protein expression. The interaction of T3 with nonhistone proteins in the chromatin initiates the thyroid hormone activity. Thyroid hormones regulate the differentiation and development of tissues and affect a number of metabolic processes. The level of circulating T3 hormone is reduced in hypothyroidism.
