PHARM 27 Flashcards
Concentrates Iodide on basolateral membrane of follicular cells
NIS (na/I symporter)
organification
thyroglobulin iodination –> MIT and DIT
catalyzes t4 –> T3
iodothyronine 5’ deiodinase
Deiodinase that is expressed in liver and kidneys, coverts serum T4
Type I
Deiodinase expressed in pituitary gland, brain, and brown fat converts T4 locally
Type II
Converts T4 - rT3
Type III Deiodinase
Two types of thyroid hormone receptors
alpha and beta
TR react with this to form heterodimers
retinoid X receptor RXR
TSH producing cells
thyrotropes
thryoid stimulating immunoglobulin
IgG autoantibody specific for TSH receptor
L-isomer of T4
levothyroxine
how does increase of hepatic p450 effect thyroid hormone?
it increases excretion
Perchlorate, thiocyanate, pertechnetate are what class of drugs
Inhibitors of iodide uptake – compete for iodide uptake into thyroid gland follicular cell
What radioactive Iodine is used as radiative treatment of hyperthyroidism?
131 I-
What is the Wolff-Chaikoff effect?
high levels of iodide inhibit thyroid hormone synthesis and release
Propylthiouracil and methimazole are what kind of drugs
Thioamines that compete with thyroglobulin for iodide – decrease organification
drugs that cause goiter
goitrogens (thioamines bc no thyroid hormone= TSH stimulation)
Inhibits thyroid peroxidase as well as peripheral T4 –> T3
propylthiouracil
only inhibits thyroid peroxidase and not peripheral T3 conversion
methimazole
Preferred b-antagonist for treatment of thyroid storm
esmolol
5’ deiodinase inhibitor
Ipodate
How does amiodarone cause hypothyroidism?
metabolism releases iodide which concentrates in thyroid gland –> wolff- Chaikoff effect
Type 1 thyrotoxicosis via amiodarone
excess iodide = increase thyroid hormone increase and release
type 2 thyrotoxicosis via amiodarone
autoimmune throiditis induced –> excess thyroid hormone from colloid
Amiodarone intrxn w 5’ deiodinase
competatively inhibits and reduces peripheral T3 conversion
L- analog of T3
Liothyronine
Rifampin and phenytoin increases the metabolism of what drug
synthetic thyroid hormone
Cholestyramine and sodium polystyrene sulfonate decrease the absorption of what drug
synthetic thyroid hormone
Used in hyperthyroidism but risk developing aplastic anemia
Percholorate
thiocyanate
pertechnetate
Used as an alternative to surgical treatment of hyperthyroidism
131 I- (may worsen ophthalmopathy
