Endocrine: Drugs for Thyroid Disorders Flashcards
How do thiocyanate and perchlorate work?
Bind to Na/I- co-transporter to decrease I entry into the thyroid gland cells
-competitive inhibitors
What is the indication for propranolol in thyroid storm?
- decreases B activation
- -decreases HR and HTN
-also inhibits 5’-deiodinase to decrease production of T3 from T4
Which drugs block the conversion of T4–>T3 by blocking 5’ deiodinase? (5)
PTU B-blockers Corticosteroids Amiodarine Radiocontrast media
What is the effect of amiodarone on the thyroid?
Greatly increases Iodine production, which is toxic to the thyroid and can cause thyrotoxicosis!
What is the MOA of methimazole?
Blocks thyroid peroxidase (TPO), which decreases the iodine organification
=less T3 and T4!
What are some major side effects of methimazole?
Agranulocytosis and aplastic anemia
Liver toxicity
–should be administered w caution if pt has liver diease
Clinical uses for potassium iodine?
Blocks iodine uptake
Can be used to treat hyperthyroidism (Wolf chiakoff effect)
Protects the thyroid from radiation exposure
-shrinks thyroid and decreases hormone production
Clinical indications for PTU?
Hyperthyroidism seen in:
- Graves
- Toxic multi-nodular goiter
MOA of PTU?
Blocks thyroid peroxidase and 5’ iodinase
-decreases production and conversion of T4–>T3
What is the most sensitive screening test to screen for hyperthyroidism and primary hypothyroidism?
TSH
MOA of levothyroxine?
Recombinant T4
-converted to T3
Side effects of of levothyroxine?
Weight loss
Trouble tolerating heat
sweating
Anxiety..etc
Basically all the symptoms of hyperthyroidism
What drugs impair levothyroxine absorption
Cholestyramine
Antacids
Iron
Sacralfate
Anything that effects absorption
How is radioactive iodine therapy used for thyroid cancer?
Thyroid gland absorbs iodine, then the iodine destroys the thyroid cells that take it up
What population is radioactive iodine contraindicated in?
Pregnant women
