Drugs for Thyroid Disorders

Question 1

Thyroid Hormones act on the ____ hormone receptor ____

Answer 1

Nuclear Hormone Receptor TRalpha/beta

Question 2

Once T3 binds to the hormone receptor, what occurs?

Answer 2

Complex move to the nucleus and begins transcription

Question 3

What is the active form of the Thyroid Hormones?

Answer 3

T4 is converted in the peripheral tissues to T3 = Active form

Question 4

What are 3 drugs that can be used to treat HYPOthyroidism?

Answer 4

Levothyroxine (T4)
Liothyronine (T3)
Liotrix (4:1 of T4:T3)

Question 5

What is Levothyroxine?

Answer 5

T4

Question 6

What is Liothyronine?

Answer 6

T3

Question 7

What is Liotrix?

Answer 7

4:1 ratio of T4:T3

Question 8

How long can the effect of Levothyroxine take to be seen?

Answer 8

Up to 6 weeks

Question 9

With excessive dosing of Levothyroxine, what adverse effects can be seen?

Answer 9

Similar to HYPERthyroidism

Question 10

What are drugs that can impair Levothyroxine absorption?

Answer 10

• CHOLESTRYAMINE

- PPIs, antacids, anti-ulcer meds, iron, etc.

Question 11

What can Cholestryamine do?

Answer 11

Impair the absorption of Levothyroxine to treat Hypothyroidism

Question 12

What drug is commonly used during a Thyroid Storm/Thyrotoxicosis to decreased HR and tremor?

Answer 12

Propranolol

Question 13

MOA for Propranolol and when is it commonly used?

Answer 13

Non-selective beta blocker

= Used to decrease HR and tremor with Thyroid storm/thyrotoxicosis

Question 14

How does Propanolol specifically treat the Hyperthyroidism?

Answer 14

(-) peripheral conversion of T4 to T3

Question 15

Which Thiamide is more potent - PTU or Methimazole?

Answer 15

Methimazole

Question 16

What are the 2 main Thiamides?

Answer 16

PTU (propylthiouracil)

Methimazole

Question 17

What is the MOA for Thiamides?

Answer 17

Block Iodide organification by preventing the addition of iodine to tryosine residues on Thyroglobulin

Question 18

When should you use caution when treating with Thiamides?

Answer 18

Agranulocytosis

Pre-existing liver disease, hepatitis, alcohol use

Question 19

Methimazole can treat Hyperthyroidism by doing what things?

Answer 19

• Preventing addition of iodine to tyrosine residues on thyroglobulin
• (-) Thyroperoxidase enzyme needed to synthesis T3/T4

Question 20

Besides treating Hyperthyroidism, when else can Methimazole be used?

Answer 20

Taken before thyroid surgery to minimize effect of thyroid manipulation

Question 21

When is PTU often used? (3)

Answer 21

Graves disease
Toxic Multinodular goiter
Thyroid storm

Question 22

When is PTU often used?

Answer 22

Graves disease
Toxic multinodular goiter
Thyroid storm

Question 23

Can PTU inactivate pre-existing T3/T4?

Answer 23

NO

Question 24

What does Potassium Iodide treat and how?

Answer 24

Hyperthyroidism

= Blocks iodide uptake

Question 25

What can treat Hyperthyroidism by blocking iodide uptake?

Answer 25

Potassium Iodide

Question 26

What anti-thyroid drug can be used to protect the thyroid from radiation exposure by shrinking it?

Answer 26

Potassium Iodide

Question 27

What can treat Thyroid Cancer?

Answer 27

Radioactive Iodine

Question 28

How does Radioactive Iodine treat Thyroid Cancer?

Answer 28

Iodine is absorbed into gland | -> Radiation destroys gland

Question 29

When should you NOT use Radioactive Iodine?

Answer 29

Pregnant women

Question 30

When should you NOT use Radioactive Iodine?

Answer 30

Pregnant women

Question 31

What normal drug can CAUSE type 2 Thyrotoxicosis?

Answer 31

Amiodarone

Question 32

What is Amiodarone used for and what can it cause?

Answer 32

Treats Arrhythmias | --> Thyrotoxicosis via thyroid tissue destruction

Question 33

What is the daily iodine recommendation?

Answer 33

0.15 mg

Question 34

How much free Iodine can Amiodarone release with each tablet?

Answer 34

7.4 mg -- way too much

Question 35

If a patient is being treated for an arrhythmia and they start to develop signs of hyperthyroidism, what drug are they likely on?

Answer 35

Amiodarone

Question 36

Type 1 Thyrotoxicosis occurs in who?

Answer 36

Patients with underlying thyroid pathology

Question 37

Type 2 Thyrotoxicosis occurs with what medication and how?

Answer 37

Amiodarone - -> thyroid tissue destruction/thyroiditis - -> excess thyroid hormones released into the circulation