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28 Cards in this Set
- Front
- Back
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propranolol
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in high doses can inhibit T4 to T3 conversion
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competitive anions
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interfere with the trapping and concentraion of iodid (I-): Thiocyanate (SCN-) and percholate (ClO4-_
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dexamethasone
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in large doses reduces the conversion of T4 to T3 and inhibits hormone release
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thisocyanate
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(SCN-) like other competitive anions not good for clinical use, toxic, produced following hyrdolysis of certain plant glycosides (cabbage and cigarret smoking; may contribue to endemic gointer where iodine in take is very lwow
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percholate
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may cause fatal aplastic anemia, used only in unusual circumstances; can be used to "discharge inorganic iodide in diagnostic test; fluoroboroate (BF4-) as effective as percholate
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where does high I- act in thyroid hormone
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(-) iodide transport into follicle cell and (-) secretion of T3 and T4
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where do thionamide drugs act
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on peroxidase (iodide to Iodine I- to I) and on peroxidase coupling reaction
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thionamide drugs are orally ____
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active
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principal site of thionamide action
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second stage of hormonogenesis; drugs are concentrated in thyroid (- peroxidse and coupling reaction)
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Propylthiouracil
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inhibits peroxidase previndting iodotyrosyl groups in thryoglobule (coupling) and organification; also interfires with peripheral 5' deiodinase conversion of T4 to T3
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drug of choice in thyroid storm
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propylthiouracil
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methimazol
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longer acting an dmore potent than propylthiolouracil
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Indications for thionamide drugs
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prpylthiouracil: sole tx of hyperthryoidism although lasting remission in graves is uncommon; in combindation with subtotal thyroidectomy; temporarily AFTER the administartion of therapeutic amounts of radioactive iodine to interfere with I131 incorporation into thyroglobulin and concentraiton in thryoid.... in olderpts bother by hyperhtryoid relation treomors use prpylthiouracil before I 131
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prphylactic use of stable Iodine
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prevents endemic goiter and hypothyroidism
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paradoxical effects of iodine (stable)
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maintains T4/T3 synthesis but can cause hyperthryoidism or inhibit T4/T3 depending on the does
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use to decrease vasculatrity of hyperhtryoid gland
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Iodine
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radioactive sodium iodide
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acts almost exclusively on the follicluar parenchymal cells (pynknosis and necrosis) can destroy gland w/o damage to surrounding tissue
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"hot" nodule on I 131
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plummer's syndrome, treat with I 131 the overactive nodule contributes to thyrotoxicosis
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a "cold" nodule on I131
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in the overactive thryoid in graves suggest surgical tx b/c of the possibility that the node may be malignant
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tx exoptalmos
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nada, responds poorly
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levothryoxine
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drug of choice for hypothyroidism, a pure syntheitic hormone, T4 SYNTHROID
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lithyronine
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T3 CYTOMEL rapid onset of action
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liotrix
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euthroid: a physiological 4:1 mix of T4: T3
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TBG has increased affinity for thyroxin ni
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estrogines, methadone, clofibrate, heroi, tamoxife, 5-fluoruracil
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estrogen TBG
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increases TBG and total T4/T3 however drop in T4/# until TSH level in crease and increase T4/T3
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androgens and TBG
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reduce TBG levels and toral serum T4/T3
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cholestyramine
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bile acid sequestrant that lowers LDL cholesterol due to cholesterol converions to bile acid BINDA AN DINHIBITS INTESTINTAL ABSORPTION OF THYROID HORMONE
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digoxin and thryoxine
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thryoxine incerases volume distribution and relnal clearanceof digoxin and can cause variable decreases in digoxin blood levels
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