Thyroid Drugs (Staudinger) Flashcards
What are the 4 thyroid hormone agonists?
- Levothyroxine (T4)
- Liothyronine (T3)
- Liotrix
- Thyroid desiccated
What are the 4 anti-thyroid agents?
- Radioactive iodine
- Potassium iodide
- Methimazole (10X more potent then PTU)
- Propylthiouracil (PTU)
Propranolol
non selective beta blocker; indicated in thyrotoxicosis (thyroid storm); reduced heart rate and tremors; inhibits peripheral conversion of T4 to T3 by blocking monodeiodinase I & II and blocks the B1 receptor on the heart
What is the most sensitive screening test for both primary hyper and hypothyroidism?
TSH
Thiocynate (SCN-) and Perchlorate (CIO4-)
environmental contaminants that inhibit the biosynthesis of thyroid hormones
Amiodarone
an anti-arrhythmic drug that can cause thyrotoxicosis due to exceeding amount of iodine released (50X); pts on this drug will need baseline thyroid hormones measured before start and then every 6-12 months afterwards
levothyroxine
T4 analogue; side effects of hyperthyroidism; has impaired absorption when taking with cholestramine
Methimazole
anti-thyroid drug; blocks iodide organification by inhibiting thyroperoxidase (necessary enzyme in T3 & T4 synthesis
Methimazole works by blocking which enzyme?
thyroperoxidase (necessary enzyme in T3 & T4 synthesis
Propylthiouracil (PTU)
anti-thyroid drug; indicated in Graves disease and pts with a toxic multi nodular goiter; use if pts are intolerant of methimazole or if pregnant; does NOT inactivate pre-existing T4 and T3 but does stop the conversion of T4 to T3
Potassium iodide
stable form of iodine; indicated in iodine deficiency; does NOT affect heart rate or produce irregular heartbeat
Drug indicated in iodine deficiency?
Potassium iodine
Radioactive Iodine (I-131)
indicated in thyroid cancer; gland absorbs the iodine and radiation destroys it; contraindicated in pregnant women
When is radioactive iodine contraindicated?
in pregnancy
Perchlorate blocking agent
competitive inhibitor of iodide uptake; indicated to control amiodarone induced thyrotoxicosis
A 24 yr old women was found to have Graves disease. The decision has begun treat with methimazole. Methimazole reduces serum concentration of T3 primarily by which of the following mechanisms?
a. accelerating the peripheral metabolism of T3
b. Inhibiting the proteolysis of thyroid-binding globulin
c. Inhibiting the secretion of TSH
d. Inhibiting the uptake of iodide by cells in the thyroid
e. Preventing the addition of iodine to tyrosine residues on thyroglobulin
e. Preventing the addition of iodine to tyrosine residues on thyroglobulin; prevent conversion of tyrosine residues in thyroglobulin to MIT or DIT
A 24 yr old women was found to have Graves disease. The decision has begun treat with methimazole. Though rare, a serious toxicity associated with the thioamides is which of the following?
a. Agranulocytosis
b. Lupus erythematous-like syndrome
c. Myopathy
d. Torsades de pointes
e. Thrombotic thrombocytes purpura (TTP)
a. Agranulocytosis (most dangerous)
Others: vasculitis, hepatic damage, and hypoprothrombinemia
