3,3',5-Triiodo-L-thyronine

Absorption

Thyroid hormones are well absorbed orally. From these hormones, liothyronine is almost completely absorbed and it does not present changes in the absorption rate due to concomitant administration of food.liothyronin Multiple administration of 50 mcg of liothyronine provided a maximal plasma concentration of total T3 of 346 ng/dL in about 2.5 hours with an AUC of 4740 ng.h/dL.

Toxicity

The reported oral LD50 of liothyronine in the rat is higher than 4540 mg/kg. When overdosage is registered, symptoms of hyperthyroidism are reported as well as confusion, disorientation, cerebral embolism, seizure, shock, coma, and death. The symptoms of overdose can be presented immediately or several days after overdose ingestion. In an overdose state, reduce the dose of liothyronine and do supportive treatment.
There are no reports studying the carcinogenic, and mutagenic potential nor on the effects of liothyronine on fertility.

Description

Crystalline T3 (liothyronine sodium, Cytomel) has a rapid onset and short duration of action. It is the therapy of choice when it is desirable to have rapid onset or cessation of activity, such as in patients with heart disease.

Chemical properties

Off-White Solid

Originator

Cytomel,SKF,US,1956

The Uses of 3,3',5-Triiodo-L-thyronine

T3 or 3,3',5-Triiodo-L-thyronine is a thyroid hormone involved with many physiological processes in the human body including growth and development, metabolism, body temperature and heart rate. Free and total T3 serum levels are measured by LC-MS/MS for determination of hyperthyroidism caused by excess T3. This Certified Spiking Solution? is suitable for use as a starting material in preparation of linearity standards, calibrators, and controls for thyroid hormone testing methods by LC-MS/MS.

The Uses of 3,3',5-Triiodo-L-thyronine

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.

The Uses of 3,3',5-Triiodo-L-thyronine

3,3’,5-Triiodo-L-thyronine (Levothyroxine EP Impurity A) is 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.

Indications

Liothyronine is officially approved for the following indications:
In general terms, exogenous liothyronine is used to replace insufficient hormonal production and restore T3 plasma levels.
The lack of liothyronine can be presented as a pale and puffy face, coarse, brittle hair, dry skin, croaky voice and constipation as well as irregular periods, drowsiness, and lethargy.
Liothyronine should never be used in the suppression of benign nodules and nontoxic diffuse goiter in iodine-sufficient patients nor in the treatment of hyperthyroidism during the recovery phase of subacute thyroiditis.

Background

Liothyronine is a thyroidal hormone T3 which is normally produced by the thyroid gland in a ratio 4:1 when compared with T4: T3. Liothyronine is the active form of thyroxine which is composed in a basic chemical structure by a tyrosine with bound iodine. The exogenous liothyronine product was developed by King Pharmaceuticals and FDA approved in 1956.

What are the applications of Application

L-3,3′,5-Triiodothyronine, free acid is a hormone produced by the thyroid gland

Definition

ChEBI: An iodothyronine compound having iodo substituents at the 3-, 3'- and 5-positions. Although some is produced in the thyroid, most of the 3,3',5-triiodo-L-thyronine in the body is generated by mono-deiodination of L-thyroxi e in the peripheral tissues. Its metabolic activity is about 3 to 5 times that of L-thyroxine. The sodium salt is used in the treatment of hypothyroidism.

What are the applications of Application

3,3′,5′-Triiodo-L-thyronine (T3) is an endocrine hormone produced by the thyroid gland and is regarded as an active thyroid hormone at cellular level. Thyroxine (T4) serves as a precursor for T3 and is generated in extrathyroidal tissues.
3,3′,5-Triiodo-L-thyronine sodium salt has been used for inducing thyroid hormone manipulations in mice. It has also been used In cell culturing of hippocampal, retinal, proximal tubule and glomerular explant.

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

Triomet-131 (Abbott); Tri-Thyrotope (Bristol-Myers Squibb).

Therapeutic Function

Thyroid hormone

Biological Activity

3,3′,5′-Triiodo-L-thyronine (T3) increases the rates of protein 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.

Biochem/physiol Actions

3,3′,5-Triiodo-L-thyronine also referred to as O-(4-Hydroxy-3-iodophenyl)-3,5-diiodo-L-tyrosine or T3 is the biologically active thyroid hormone. In hypothyroidism pateints, triiodothyronine enhances mood and neuropsychological function. The product also positively regulates the hepatic FGF21 expression and stimulates the metabolic breakdown of glucose, fats, and proteins by enhancing the levels of numerous metabolic enzymes such as hexokinase, liver glucose 6-phosphatase as well as mitochondrial enzymes for oxidative phosphorylation. Additionally, the product facilitates the normal body growth in children and is pivotal for central nervous system maturation in foetus.

Pharmacokinetics

In hormonal replacement, liothyronine is more potent and present a faster action when compared to levothyroxine but the time of action is significantly shorter. The type of treatment needs to be well evaluated as the fast correction of thyroid hormones in certain diseases presents additional risks such as heart failure. The onset of activity is observed a few hours after administration and the maximum effect is observed after 2-3 days.
Treatment with liothyronine has been shown to produce normal plasma levels of T3 hormone but to have no effect on the T4 plasma concentration.

Metabolism

Liothyronine is mainly metabolized in the liver where it is deiodinated to diiodothyronine and monoiodothyronine followed by conjugation with glucuronides and sulfates. One of the formed metabolites formed by the conjugation and decarboxylation is tiratricol. The iodine released by the metabolism of liothyronine is later taken and used within the thyroid cells.

storage

-20°C

Purification Methods

Likely impurities are as in thyroxine. Purify it by dissolving in dilute NH3 at ~20o, then crystallise it by addition of dilute acetic acid to pH 6. Alternatively 35g are purified by dissolving it in a mixture of EtOH (250mL) and 2N NaOH (100mL), then hot 2N HCl is added to the boiling solution until the pH is 4-5. After cooling for a few hours, the solid is filtered off and dried in a vacuum [m 233-235o(dec)]. [Chambers et al. J Chem Soc 2433 1949, Beilstein 14 III 1566, 14 IV 2373.]