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| Primary information |
|---|
| ID | 13025 |
| Therapeutic ID | Th1377 |
| Protein Name | Thyroid, porcine |
| Sequence | >Th1377_Thyroid,_porcine
MGARAVLGVTLAVACAGAFFASILRRKDLLGGDTEASGVAGLVEASRLLVDEAIHTTMRRNLRKRGIFSPSQLLSFSKLPEPTSRTASRAAEIMETAVQEVKRRVCRRRDTDQLPTDVLSEELLSTIANLSGCLPHMLPPSCPHTCLANKYRLITGACNNRDHPRWGASNTALARWLPPAYEDGVTEPRGWNPHFLYNGLPLPPVREVTRQVIHVSNEAVTEDGQYSDLLMAWGQYIDHDIAFTPQSTSKAAFAGGADCQLTCENRSPCFPIQLPTNASGAAGATCLPFYRSSAACGSGRQGALVGNLSWAAPRQQMNGLTSFLDASTVYGSSPAQEQRLRNWTSAEGLLRVNTRHRDAGRAFLPFAPPPAPPACAPEPGTPAARAPCFLAGDSRASEVPGLTALHTLWLREHNRLAAAFKALNAHWSADTVYQEARKVVGALHQIVTLRDYVPKILGAEAFGQHVGPYQGYDPAVDPTVSNVFSTAAFRFGHATIHPLVRRLDARFQEHPGSHLPLRAAFFQPWRLLREGGVDPVLRGLLARPAKLQVQDQLMNEELTERLFVLSNSGTLDLASINLQRGRDHGLPGYNEWREFCGLSRLETWADLSAATANGRVADRILGLYQHPDNIDVWLGGLAESFLPGARTGPLFACIIGKQMRALRDGDRFWWENPGVFTEAQRRELSRHSMSRVICDNSGLSHVPLDAFRVGQWPQEFEPCASIQGMDLGAWREAPPSGDACGFPDPVEDGGFLLCEERGQRVLVFSCRHGFRLRGPAQITCTPRGWDSPPPLCKDINECEDETDPPCHASARCKNTKGGVLCECSDPLVLGEDGRTCVDAGRLPRASVVSIALGAVLVCGLAGLAWTVVCRWTHADARPLLPVGEGEGDGKSPSLPLPGCGNRRDVGAAPALEVEQDLSCGSRGLCE
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| Molecular Weight | NA |
| Chemical Formula | NA |
| Isoelectric Point | NA |
| Hydrophobicity | NA |
| Melting point | NA |
| Half-life | Data regarding the half life of thyroid extract is not readily available as it is a mixture of many compounds.[L11755] Levothyroxine, a synthetic form of T4, has a half life of 6.2 days in euthyroid patients and 7.5 days in hypothyroid patients.[A190894] T3 has a half life of 1.0 days in euthyroid patients and 1.4 days in hypothyroid patients.[A190894] |
| Description | Thyroid extract is dried and powdered thyroid glands from pigs containing tiiodothyronine (T3) and thyroxine (T4) used to supplement low or absent thyroid activity.[A190831,L11755] Thyroid extract has been described in literature to treat hypothyroidism since 1891[A190807] but its use dates back as far as the 6th century.[A190831] Thyroid extract is no longer considered a first line therapy as it delivers a dose that is inconsistent with the stated strength of the tablet.[A190813] Currently, patients are more likely to be treated with [levothyroxine].[A190813] Thyroid extracts were never FDA approved as their use in the United States predates the FDA.[A190831] |
| Indication/Disease | Thyroid extract is indicated for replacement therapy in decreased or absent thyroid function.[L11755] |
| Pharmacodynamics | Thyroid extract increases the metabolic rate of patients with hypothyroidism.[A190906,A190909] The therapeutic index of thyroid extract is wide, as patients can be given varying doses.[L11755] The duration of action is long as thyroid extract is generally given once daily.[L11755] Patients should not use thyroid extract for weight loss.[L11755] |
| Mechanism of Action | T3 binding to the thyroid hormone receptor (TR), changes the conformation of the TR, allowing it to bind to the retinoid X receptor (RXR) and form a coactivator complex.[A190906] The coactivator complex has histone acetyltransferase activity, which activates genes.[A190906] In the absence of T3, TR and RXR form a corepressor complex with histone deacetylase activity, which represses genes.[A190906] The macroscopic effects of thyroid hormones is an increase in the metabolic rate.[A190909] T4 has similar but weaker activity to T3.[A190909] |
| Toxicity | Patients experiencing and overdose may present with symptoms of a hypermetabolic state.[L11755] Overdose may be treated by symptomatic and supportive treatment, dose reduction or temporarily stopping the medication, induction of vomiting, administering oxygen, cardiac glycosides, as well as methods to control fever, hypoglycemia, and fluid loss.[L11755] |
| Metabolism | Approximately one third of the active T4 is deiodinated to the active T3, one third is deiodinated to the inactive reverse T3 (rT3), and one third is glucuronidated or sulfated.[A190903] Deiodination is mediated by iodothryonine deiodinases, glucuronidation is mediated by glucuronyltransferases, and sulfation is mediated by sulfotransferases.[A190903,A190894] T3 and rT3 are further deiodinated to diiodothyronine (T2), iodothyronine (T1), and their reverse forms.[A190894] T4 can also undergo ether bond cleavage or oxidative deamination but these pathways are incredibly minor.[A190903] |
| Absorption | T4 is 48-79% absorbed in the gastrointestinal tract and T3 is 95% absorbed.[L11755] L-triiodothyronine reaches a Cmax of 320±60ng/L, with a Tmax of 1.8±0.3h.[A190900] Levothyroxin has a Tmax of2-3h.[A190894] |
| Data regarding the volume of distribution of thyroid extract is not readily available as it is a mixture of many compounds.[L11755] Levothyroxine, a synthetic form of T4, has a volume of distribution of 11-15L.[A190894] L-triiodothyronine, a synthetic form of T3, has an apparent volume of distribution of 14.9±4.2L.[A190900] |
| Clearance | Data regarding the clearance of thyroid extract is not readily available as it is a mixture of many compounds.[L11755] The clearance of levothyroxine, a synthetic form of T4, is 0.044L/h in euthyroid patients and 0.038L/h in hypothyroid patients.[A190894] |
| Categories | Agents used to treat hypothyroidism |
| Patents Number | NA |
| Date of Issue | NA |
| Date of Expiry | NA |
| Drug Interaction | NA |
| Target | Thyroid hormone receptor alpha,Thyroid hormone receptor beta |
| Brand Name | Armour Thyroid |
| Company | Physicians Total Care, Inc. |
| Brand Description | Physicians Total Care, Inc. |
| Prescribed For | Oral |
| Chemical Name | 90 mg/1 |
| Formulation | Thyroid hormone preparations are generally contraindicated in patients with diagnosed but as yet uncorrected adrenal cortical insufficiency, untreated thyrotoxicosis, and apparent hypersensitivity to any of their active or extraneous constituents. There is no well-documented evidence from the literature, however, of true allergic or idiosyncratic reactions to thyroid hormone. |
| Physical Appearance | hair loss during the first few months of treatment |
| Route of Administration | NA |
| Recommended Dosage | Armour Thyroid is a prescription medicine used to treat the symptoms of low thyroid hormone (Hypothyroidism). Armour Thyroid may be used alone or with other medications. |
| Contraindication | NA |
| Side Effects | Armour® Thyroid (thyroid tablets, USP)* for oral use is a natural preparation derived from porcine thyroid glands and has a strong, characteristic odor. (T3 liothyronine is approximately four times as potent as T4 levothyroxine on a microgram for microgram basis.) They provide 38 mcg levothyroxine (T4) and 9 mcg liothyronine (T3) per grain of thyroid. The inactive ingredients are calcium stearate, dextrose, microcrystalline cellulose, sodium starch glycolate and opadry white. |
| Useful Link 1 | Link |
| Useful Link 2 | Link |
| Remarks | NA |