Thyroid hormone synthetic

Indications Hypothyroidism Category Thyroid hormone, synthetic Half-life 6-7 days... 

Structure—Activity Relationships. In spite of the considerable synthetic and bioassay effort involved in estabhshing the thyromimetic potency of thyroid-hormone analogues, more than 100 compounds have been studied (Table 2). The main stmctural requirements for thyromimetic activity can be summarized as follows (6,12—16). 

The TAAR receptor system has also been associated with body temperature regulation on the basis of putative thyroid hormone metabolites and their synthetic derivatives (thyronamines) activating TAAR1 in rodents. However, as these effects are only observed with thyronamine concentrations several orders of magnitude above physiological levels, and as the specificity of these compounds has not been determined, the physiological significance of these observations is unclear. 

Thyroid hormones used in medicine include both the natural and synthetic hormones. The synthetic hormones are generally preferred because they are more uniform in potency than are the natural hormones obtained from animals. Thyroid hormones are listed in the Summary Drug Table Thyroid and Antithyroid Dragp. 

Despite the availability of a wide array of thyroid hormone products, it is clear that synthetic levothyroxine (LT4) is the treatment of choice for almost all patients with hypothyroidism. LT4 mimics the normal physiology of the thyroid gland, which secretes mostly T4 as a prohormone. As needed, based on metabolic demands, peripheral tissues convert thyroxine (T4)... 

Excessive doses of thyroid hormone may lead to heart failure, angina pectoris, and myocardial infarction. Allergic or idiosyncratic reactions can occur with the natural animal-derived products such as desiccated thyroid and thyroglobulin, but they are extremely rare with the synthetic products used today. Excess exogenous thyroid hormone may reduce bone density and increase the risk of fracture. 

Q76 Levothyroxine sodium is the synthetically prepared sodium salt of the natural isomer of thyroid hormone. Levothyroxine sodium tablets are unstable and require administration on an empty stomach. 

Levothyroxine is used to treat hypothyroidism (an underactive thyroid gland). Thyroid hormone can be made from beef and pork thyroid, but this lacks standardization and it is difficult to control dosage. The synthetic drug is more desirable. Levothyroxine is one of two important thyroid hormones. It is converted into the second important hormone, liothyronine, in the body. The key step in the synthesis of structures such as levothyroxine is the substitution of an iodonium salt by an iodinated phenol. Siql-like reactions on an aromatic ring are not common, but an iodonium salt provides a good leaving group. 

Thyroid Hormone and Antithyroid Drugs, Pages 337-342 26.lnsulin and Synthetic Hypoglycemic Agents, Pages 343-348... 

Retinoids are a family of naturally occurring and synthetic analogues of vitamin A. The skin of subjects deficient in vitamin A becomes hyperplastic and keratotic (phrynoderma, or toad skin). While natural vitamin A is occasionally employed therapeutically, synthetic retinoids are more effective and represent a major advance in dermatological pharmacotherapy. Retinoids have myriad effects on cellular differentiation and proliferation it is likely that nuclear retinoic acid receptors mediate these effects by activating gene expression in a manner analogous to receptors for steroid hormones and thyroid hormones. Despite a common mechanism of action, however, retinoids vary widely in their physiological effects. 

Mechanism of Action A synthetic form of triiodothyronine (T3), a thyroid hormone involved in normal metabolism, growth, and development. Possesses catabolic and anabolic effects. Therapeutic Effect Increases basal metabolic rate, enhances gluco-neogenesis, and stimulates protein synthesis. 

The only effective treatment is replacement therapy with thyroid hormones. Levothyroxine, a synthetic levoisomer of thyroxine (T4), is the drug of choice since it is stable, relatively inexpensive, free of antigenicity, and of uniform potency. It results in a pool of thyroid hormone that is rapidly converted into the more potent T3. Levothyroxine can be administered orally or... 

Several natural or synthetic substances interfere with the synthesis and/or secretion of the thyroid hormones. Two types of thionamides are used in the treatment of hyperthyroidism ... 

Shibata H, Hayakawa H, Hirukawa M, Tadokoro K, Ogata E. Hypersensitivity caused by synthetic thyroid hormones in a hypothyroid patient with Hashimoto s thyroiditis. Arch Intern Med 1986 146(8) 1624-5. 

Cytomel is the synthetic form of T-3/L-triiodothyronine and was a commonly known trade or brand name among athletes. T-3/L-triiodothyronine is used as a form of thyroid hormone therapy mostly in Europe. Most bodybuilders favored this drug over synthetic forms of T-4/L-thyroxine due to its vastly superior activity level. 

The abuse of synthetic T-3/L-triiodothyronine will result in severe suppression of natural (endogenous) thyroid function. This is especially true of this drug because it actually circumvents the normal thyroid hormone manufacturing process the body utilizes to produce endogenous forms as required. Simplified this is because T-3/L-triiodothyronine is the most potent thyroid hormone so the body shuts down each level required for production to try to reduce circulatory T-3/L-triiodothyronine levels. Of course this does not reduce the level if the hormone is being administered exogenously (from outside the body). 

Some athletes used guggulsterones to regenerate thyroid function after discontinuance of synthetic T-3/T-4 protocols. Those who thought ahead, utilized guggulsterones " synthetic T-3/T-4 thyroid hormone use to prevent thyroid function suppression even temporarily. This usually was initiated 10-14 days prior to synthetic thyroid administration discontinuance. Coleus Forskohlii, the amino acid tyrosine, and iodine also had a noted great deal of value for this purpose. 

Drug Class Synthetic Thyroid Hormone. (Oral)... 

There are two well known synthetic thyroid hormones commonly administered by bodybuilders known as T-4 and T-3. ( See "Synthroid" and "Cytomel" for more info) However, some have not yet heard of another natural thyroid hormone called T-2 or L-diiodothyronine. The good new is that it is highly active and naturally occurring in some foods such as beef products. It is also non-prescription in many countries...so far. The bad news is that since it works quite well and offers individuals freedom of choice, it probably will not be legal for long. 

Triacana is a trade or brand name for the thyroid drug Tiratricol. The body naturally (endogenously) produces T-4/L-thyroxine, T-3/L-triiodothyronine, and T-2 /L-diiodothyronine. Triacana is simply a synthetic form of these three thyroid hormones natural metabolite product, Triiodothyroacetic acid, or tiratricol for short. This means the body naturally produces Triacana as a metabolic by-product of other thyroid hormones. 

Ephedrine both suppress natural insulin release, they usually stacked the GH and Clenbuterol /Ephedrine with a synthetic T-3 thyroid hormone and sometimes with insulin as well. The use of insulin was dependent upon whether it was a bulking or dieting phase and depending on how their body responded to exogenous insulin use. 

Failure of the thyroid to produce sufficient thyroid hormone is the most common cause of hypothyroidism and is known as primary hypothyroidism. Secondary hypothyroidism occurs much less often and results from diminished release of TSH from the pituitary. Treatment of hypothyroidism is achieved by the replacement of thyroid hormone, primarily T4. A synthetic preparation of T4 is available, levothyroxine (Synthroid ), which has been a popular choice for hypothyroidism because of its consistent potency and prolonged duration of action. No toxicity occurs when given in physiological replacement doses. Desiccated animal thyroid is also available at a lesser cost. Overdoses cause symptoms of hyperthyroidism and can be used as a guide in clinical management. Hypothyroidism is not cured by the daily intake of thyroid hormone it is a life-long regimen. 

There are many types of steroid hormones in the body, such as the sex/gonadal hormones testosterone and estrogen, thyroid hormones, growth hormones, and stress hormones, which serve various normal functions. One type of steroid— corticosteroids or glucocorticoids—is secreted by the adrenal glands (located just above the kidneys). These steroids, particularly synthetic versions of them, have powerful antiinflammatory actions that help to relieve pain. They are often given as an epidural injection to relieve neck or back pain that results from a compressed or pinched nerve. They can also be injected directly into a joint to relieve pain caused by inflammation in conditions such as tendonitis (inflammation of the tendons), carpal tunnel syndrome, tennis elbow, bursitis (inflammation of sac-like cavities in tendons or muscles that allow them to slide easily over bone), or other joint pain. Professional athletes, who routinely experience one or more of these conditions, are often given local steroid injections. Frequently, the steroid is combined with a local anesthetic such as lidocaine. 

The thyroid hormones, exemplified by thyroxine, provide another case where NMR relaxation time measurements give an insight into internal flexibility, and perhaps mode of action, of pharmaceutically important molecules. Synthetic thyroxine, 5, is widely used for the treatment of thyroid disorders, and indeed was the second most widely prescribed drug in the United States in 1998. 

Mitsuma,T., and Nogimori,T. (1984), Changes in plasma thyrotrophin-releasing hormone, thyrotrophin, prolactin and thyroid hormone levels after intravenous, intranasal or rectal administration of synthetic thyrotrophin-releasing hormone in man, Acta Endocrinol., 107, 207-212. 

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