Thyroid and antithyroid preparations

The main role of the human thyroid gland is production of thyroid hormones (iodinated amino acids), essential for adequate growth, development, and energy metaboHsm (1 6). Thyroid underfunction is an occurrence that can be treated successfully with thyroid preparations. In addition, the thyroid secretes calcitonin (also known as thyrocalcitonin), a polypeptide that lowers excessively high calcium blood levels. Thyroid hyperfunction, another important clinical entity, can be corrected by treatment with a variety of substances known as antithyroid dmgs. 

Kirk-Othmer Encyclopedia of Chemical Technology (4th Edition) 

Myxedema and goiter are the main conditions for which thyroid preparations are indicated. The treatment of cretinism is difficult because it is recognized only at or after birth. Even if this disease could be diagnosed m utero, thyroid hormones do not readily cross the placental barrier. In addition, the fetus, as does a premature infant, rapidly deactivates the thyroid hormones. The halogen-free analogue DlMlT [26384-44-7] (3), which is resistant to fetal deiodinases, may prove useful for fetal hypothyroidism (cretinism). 

Stmctures of the thyroidal iodinated amino acids and the halogen-free analogue DlMlT (3). Compound (4) is reverse-T.  

For many years it was believed that iodine, or some other halogen, had to be present to endow these compounds with thyromimetic activity. This was shown to be incorrect when a halogen-free analogue, DIMIT (3), was found to have 20% of the potency of T4 in a variety of in vivo tests (12). 

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Amino acid-derived hormones include the catecholamines, epinephrine and norepinephrine (qv), and the thyroid hormones, thyroxine and triiodothyronine (see Thyroid AND ANTITHYROID PREPARATIONS). Catecholamines are synthesized from the amino acid tyrosine by a series of enzymatic reactions that include hydroxylations, decarboxylations, and methylations. Thyroid hormones also are derived from tyrosine iodination of the tyrosine residues on a large protein backbone results in the production of active hormone. 

Iodine. Of the 10—20 mg of iodine in the adult body, 70—80 wt % is in the thyroid gland (see Thyroid and antithyroid preparations). The essentiahty of iodine, present in all tissues, depends solely on utilisation by the thyroid gland to produce thyroxine [51-48-9] and related compounds. Well-known consequences of faulty thyroid function are hypothyroidism, hyperthyroidism, and goiter. Dietary iodine is obtained from eating seafoods and kelp and from using iodized salt. 

Pharmaceuticals, chiral) Prostaglandins Psycopharmacologicalagents Steroids Thyroid and antithyroid preparations Veterinary drugs and Vitamins. 

USP XXII specifies that sodium iodide contains 99—101.5% Nal, calculated on an anhydrous basis (4). It is used iaterchangeably with potassium iodide as a therapeutic agent, except where sodium ion is contraindicated (see Potassium compounds). Intravenous sodium iodide formulations have been used for a variety of diseases, from thyroid deficiency to neuralgia (see Thyroid and antithyroid preparations). However, these solutions are no longer listed ia the XFXUII (4), iadicatiag that their therapeutic value has not been satisfactorily demonstrated. 

Myxedema -role of the thyroid [THYROID AND ANTITHYROID PREPARATIONS] (Vol 24)... 

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