Synthetic thyroxine

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. 

Salbutamol works by imitating the action of a hormone thyroxine is a hormone—it is part of the body s control over its metabolic rate. Lack of thyroxine (or rather, of the iodine needed to make it) causes hyperthyroidism, or goitre. Our next synthesis is one that has been used on an industrial scale for the manufacture of synthetic thyroxine (identical with, but less macabre than, naturally extracted thyroxine). 

Synthroi(f contains synthetic thyroxine as the active ingredient. 

Synthetic thyroxine has been available since 1949 when Hems and his associates [176, 177] succeeded in developing a commercially feasible synthesis of the thyroid hormone. More recently, Meltzer and Stanabeck [178] have developed a more practical synthesis of this hormone. These investigators have incorporated in their synthesis the estabhshed principles of the bios5mthesis of th3n oxine that is, the oxidative coupling of 4-hydroxy-3,5-diiodophenyl-pyruvic acid and 3,5-diiodot5n osine. 

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)... 

Levothyroxine (also marketed as Levoxyl, Levothroid, Synthroid, or L-thyroxine sodium) is the only thyroid system prescription that has recently featured prominently among the top 200 medications in the United States. Thus, 75.1 million, 80.7 million, and 79.4 million levothyroxine prescriptions were dispensed in 2003, 2004, and 2005, respectively. At these rates, levothyroxine by itself comprised 3.5, 2.9, and 3.4% of the total prescriptions in the top 200 most popular drugs in the United States in 2003, 2004, and 2005, respectively, making it the most prescribed drug. Levothyroxine is a synthetic version of the natural hormone thyroxine, which is released by the thyroid gland. The natural hormone is important in the development of fetuses and newborns, playing a role in cmcial processes such as the development... 

Hypothyroidism can occasionally be treated with a regular intake of iodide, but in the case of non-functioning of the gland thyroxine must be used. Synthetic levothyroxine... 

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... 

All of these naturally occurring molecules are levo (l) isomers. The synthetic dextro (d) isomer of thyroxine, dextrothyroxine, has approximately 4% of the biologic activity of the L-isomer as evidenced by its lesser ability to suppress TSH secretion and correct hypothyroidism. 

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. 

Synthroid is a man-made synthetically manufactured version of T-4/L-thyroxine. The average person produces about 76 MCG/d of T-4/L-thyroxine which is then converted by the liver into the more active T-3/L-triiodothyronine. This is true of the oral T-4/L-thyroxine medications as well. The average conversion rate of T-4 to T-3 is about 30-33%/ MCG. Since the conversion of T-4 to T-3 is dependent upon adequate levels of since and selenium, athletes commonly increase daily intake of these minerals during synthetic T-4/L-thyroxine use. 

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. 

Uridine 5 -carboxylic acid, testosterone-17-hemisuccinate, mono-succinyl ecdysterone, 3-O-succinyldigitoxigenin, cholic acid, thyroxine, prostaglandins, synthetic estrogens, clonazepam-3-hemisuccin-ate, and reserpine are among the compounds linked in this way. 

Any of the commercially available thyroid preparations accomplish this goal (Table 73-8) however, levothyroxine (1-thyroxine) is considered to be drug of choice. The thyroid preparations are either natural (i.e., desiccated thyroid and thyroglobulin) or synthetic (levothyroxine, fiothyronine, and fiotrix) in origin. The availability of sensitive and specific assays for total and free hormone levels as well as TSH... 

Levothyroxine Synthroid, Levothroid, and other generics 25-, 50-, 75-, 88-, 100-, 112-, 125-, 137-, 150-, 1 75-, 200-, 300-mcg tablets 200-and 500-mcg/vial injection Levoxyl, Thyro-Tabs, Unithroid Synthetic T4 50-60 meg Stable predictable potency generics are bioequivalent when switching from natural thyroid to t-thyroxine, lower dose by 1/2 grain variable absorption between products half-life = 7 days, so daily dosing considered to be drug of choice... 

Synthroid is a synthetic form of the thyroid hormone thyroxine (T-4). Thyroxine was the first thyroid hormone isolated by scientists, who at first mistakenly thought it was the primary thyroid hormone. Later we have come to find however that T-3 is the hormone which displays the most activity. Thyroxine is actually looked at as a relatively inactive thyroid product in its initial state, and exerts most of its action by converting to T-3. 80% of blood T-3 actually comes from... 

The thyroid hormone thyroxine, (204), is reported to yield a complex mixture of products when irradiated with u.v. light. However, the synthetic hormone analogue (205) photocyclises in fair yield to the dibenzofuran (206). Intramolecular displacement of ortho halide is also reported to occur in the photocycllsation of (207) to (208), and in (209) to (210), and for the enolate of... 

Formation of Thyroxine and Triiodothyronine from lodotyrosines. The remaining synthetic step is the coupling of two diiodotyrosyl residues to form or of one monoiodotyrosyl and one diiodotyrosyl residues to form Tj. The same peroxidase catalyzes these oxidative reactions. The conformation of thyroglobulin apparently renders it uniquely efficient for the couphng reaction. T predominantly is formed at the amino terminus of thyroglobulin, while Tj is preferentially localized to the carboxy terminus. 

---