thyroid pharm

Question 1

Thyroid agents

Answer 1

levothyroxine (T4)

liothyronine (T3)

Question 2

antithyroid agents

Answer 2

methimazole
PTU
potassium iodine
radioactive iodine

Question 3

what will block the Na/I cotransporter?

Answer 3

thiocyanate (SCN)
pertechnetate
perchlorate

Question 4

high intrathyroidal iodine can block what?

Answer 4

thyroidal peroxidase

Question 5

what can inhibit 5’deiodinase

Answer 5

amiodarone
iodinated contrast media
beta-blockers
corticosteroids 
severe illness
starvation
PTU

Question 6

MOA of thyroid hormones

Answer 6

• T4 -> T3 via cytoplasmic 5-deiodinase
• T3 into nucleus
• TR bound to DNA TRE
• T3 binds TR and displaces corepressor
• activated TR binds RXR -> transcription

Question 7

T4 absorption

Answer 7

in duodenum and ileum

must be given 1 hr before meals or 4 hours after meals and other drugs

Question 8

which thyroid drug more bioavailable?

Answer 8

liothyronine

Question 9

severe myxedema with ileus

Answer 9

can decrease absorption of TH and should be given IV

Question 10

metabolism of TH in hyperthyroidism

Answer 10

clearance is increased

half-life is decreased

Question 11

metabolism of TH in hypothyroidism

Answer 11

clearance is decreased

half-life is increased

Question 12

agents which increase hepatic metabolism of TH

Answer 12

rifampin
phenobarbital
carbamazepine
phenytoin
HIV protease
inhibitors

Question 13

agents which interfere with T4 absorption

Answer 13

PO biophosphates
bile acid sequestrants
cipro
proton pump inhibitors
sucralfate
anacids
bran
soy
coffee

Question 14

agents which induce autoimmune thyroid disease

Answer 14

interferon
lithium
amiodarone

Question 15

what is the TH drug of choice

Answer 15

levothyroxine

Question 16

why is liothyronine not the drug of choice

Answer 16

it is more potent, but has shorter half life and must be dosed more often
more expensive
difficult to monitor
has greater cardiotoxicity effects

Question 17

desiccated TH

Answer 17

never should be used

Question 18

thioamides MOA

Answer 18

prevent TH synthesis:
block peroxidase
block organification
blocks coupling of MIT and DIT to TG
PTU also inhibits T4 -> T3
onset of action is 3-4wks

Question 19

methimazole

Answer 19

drug of choice
10x more potent then PTU
completely absorbed
safe for breast feeding

Question 20

PTU

Answer 20

used in pregnancy and thyroid storm

Question 21

thioamides common ADRs

Answer 21

most common is maculopapular rash
fever
GI and nausea

Question 22

thioamides rare ADRs

Answer 22

urticarial rash
vasculitis
lupus-like rxn
lymphadenopathy
hypoprothrombinemai
exfoliative dermatitis
acute arthralgias
cholestatic jaundice

Question 23

block box warning of PTU

Answer 23

severe hepatitis

Question 24

most dangerous complication of thioamides

Answer 24

agranulocytosis (<500)
must discontinue
cannot switch they x-react

Question 25

potassium iodide MOA

Answer 25

inhibit iodine organification and hormone release decrease size and vasulcarity of gland *inhibits hormone release

Question 26

uses of potassium iodine

Answer 26

thyroid storm preoperative reduction of hyperplastic gland block thyroidal uptkae of radioactive isotopes in radiation emergency never can be used alone b/c effects wear off in 2-8 weeks and will become have rebound avoid if near future radiation Tx will be used

Question 27

ADRs of potassium iodine

Answer 27

``` uncommon rash swollen salivary glands mucous membrane ulcerations conjuctivitis rhinorrhea drug fever metallic taste bleeding anaphylaxis ```

Question 28

CI of potassium iodine

Answer 28

pregnancy

Question 29

CI of radioactive iodine

Answer 29

pregnancy or breast feeding

Question 30

adrenoreceptor-blockers

Answer 30

metroprolol propanolol atenolol

Question 31

how long does it take for levothyroxine to reach steady state

Answer 31

6-8wks

Question 32

myxedema common

Answer 32

end stage of untreated hypothyroidism medical emergency ICU with intubation and mechanical ventilation loading IV levothyroxine hydorcortisone IV if they have coronary aa disease must correct very cautiously

Question 33

what is the preferred patient population for antithyroidal drugs

Answer 33

young patients with small glands and mild disease

Question 34

thyroidectomy preferred patient population

Answer 34

large glands or multi-nodular goiters | must obtain euthyroid via pharm before sugery

Question 35

RAI preferred patient population

Answer 35

almost everyone 21+ | heart disease

Question 36

adjunct to antithyroid therapy

Answer 36

beta-blockers | diltiazem

Question 37

thyroid storm

Answer 37

``` beta blocker potassium iodine PTU hydorcortisone supportive therapy if really bad can give oral bile sequestrants, plasmapheresis, or peritoneal dialysis ```