Drugs for thyroid disorders

Question 1

what are the thyroid agents

Answer 1

levothryoxine (T4)

liothyronin (T3)

Liotrix

Thyroid Desiccated

Question 2

what are the antithyroid agents

Answer 2

Radiosctive iodine (131I)

potassium iodide

methimazole

propylthiouracil (PTU)

Question 3

thyroid storm is also known as _ and _ and can be treated with?

Answer 3

thyrotoxicosis and symptomatic hyperthyroidism

propranolol

Question 4

what is propranolol and what does it do?

Answer 4

it is a non-selective beta 1 and beta 2 blocker

it is used to reduce heart rate and tremor during a thyroid storm - its MOA is to inhibit the conversion of T4 to T3 in peripheral tissues

also may help to reduce systemic vascular resistance

Question 5

why is propranolol preferred to other beta blockers in thyrotoxicosis/thyroid storm?

Answer 5

it blocks monodieiodinase type I and type II which stops the conversion of T4 to T3 (active)

it also inhibits the cardiovascular symptoms that occur in thyroid storm (termor, shakes, increased BP and pulse)

works at 2 levels

Question 6

TSH is _ in primary hypothyroidism

TSH is _ or _ in secondary or tertiary hypothyroidism

Answer 6

high

normal or low

Question 7

_ is the most sensitive screening test for hyperthyroidism and primary hypothyroidism

Answer 7

TSH

Question 8

what is the thyroid receptor

Answer 8

a nuclear hormone receptor with a zinc finger DNA binding domain, ligand binding domain and 2 activation function domains

has alpha and beta subuits and is activated by thyroid hormones

ligand activating transcription factors - superfamily

Question 9

TSH is also known as?

Answer 9

thyrotropin

Question 10

describe thryoid hormone synthesis

Answer 10

thyroglobulin is iodinated at its tyrosine residues and is conjugated, eventuallly it is exocytosed and undergoes proteolysis to form T4 and T3

Question 11

SCn and CIO4 both inhibit what step of thyroid hormone synthesis

thicyanate and perchlorate

Answer 11

they inhbit the uptake of iodide into the thyroid gland

Question 12

iodide is transformed into iodine by what

Answer 12

peroxidase

Question 13

what blocks iodine from being integrated into thyroglobulin

Answer 13

iodides and thioamides

Question 14

what blocks the proteolysis step of thyroglobulin into T4 and T3

Answer 14

iodides

Question 15

what blocks the peripheral conversion of T4 to T3 in tissues

Answer 15

radiocontrast, B blockers, corticosteroids, amiodarone

Question 16

what is amiodrone?

what does it cause?

Answer 16

it is a commonly use anti-arrhythmic that is used to treat ventricular arrhythmia, atrical fibrillation ect.

it can cause type II amidodrone induced thyrotoxicosis which results from destruction of the thyroid tissue

you must get baseline levels of TSH, T3 and T4 to monitor for the emergence of hyperthroidism symptoms

Question 17

each 200 mg tablet of amiodarone contains _ iodine and _ is released as free iodine. This means that the dosing is toxic/50 fold higher.

Answer 17

74.4mg

7.4mg

Question 18

what is levothyroxine

Answer 18

L-thyroine

that is used to treat throid hormone deficinecy that is given in the T4 form

it is peripherally converted to T3 in the body and can take up to 6 weeks to work

Question 19

side effects of levothyroxine and how is dosing measured

Answer 19

Side effects: weight loss, tremor, sweating, anxiety, trouble sleeping, fast heart rate

dosing is based on regular measurments of TSH and T4 in the patients blood

Question 20

what drugs can impair levothyroxine absorption?

Answer 20

cholestyramine , antacids, iron etc.

Question 21

what are the thioamides?

Answer 21

carbimazole
methimazole
propylthiouracil

Question 22

carbimazole is converted to?

Answer 22

methimazole

Question 23

which one is more potent : methimazole or PTU

Answer 23

methimazole

Question 24

what is methimazole

Answer 24

this is an antithyroid drug that is used to treat graves disease

it blocks thyroid peroxideses which blocks iodide organification

it is taken before surgert to lower thyroid levels and minmize the effects of thyroid manipulation

Question 25

side effects of methimazole

Answer 25

agranulocytosis, leukopenia, thrombocytopenia, liver inflammation

monitor people with preexisiting liver diease, with alcohol abuse, or hepatitis

Question 26

what is PTU

Answer 26

this is an thioamide that blocks the synthesis of thyroid hormones by inhibiting the conversion of thyroxine to triiodethyronine

it is used in graves disease or in people with a toxic multinodular goiter

works only on endogenous throid hormones

can use if patient cant tolerate methimazole, can be used before surgery, can be used with radioactive iodine

Question 27

potassium iodie is a stable form of _ that blocks _ uptake. It is used to treat _ and _

Answer 27

iodine

iodine uptake

hyperthyroidism and idodine def.

can be used along with outer anti-thyroid meds to prepare for surgery

Question 28

potassium iodide is also used to protect the thyroid from _. it shrinks the gland and decreases thyroid hormone production

Answer 28

radiation

it DOES NOT AFFECT HEART RATE

Question 29

what is radioactive iodine (I131)

Answer 29

this is a therapy for thyroid cancer that destroys the thyroid gland and the cancerous cells

category D in pregnancy- do not use

has little effect else where in the body

Question 30

what beta blockers are used in graves diease and thyroid storm

what is the MOA

and which one is used more, which one has less cerebral effects

Answer 30

propranolol, metopropol, atenolol

stabalizes the membrane to inhbit T4 to T3 conversion and stops symtpoms of hyperthyroidism and also blocks Beta receptors to stop catecholamine release

propranolol used more

atenolol- less cerebral effects

Question 31

what is perchlorate

Answer 31

this inhibits thryoid hormone production by being a competitive inhibitor of iodide uptake by the thyroid gland

• it blocks the sodium-iodie synmporter
• used to control amiodarone induced thyoid dysfunction

there is no effect on the iodination process