Thyroid drugs

Question 1

Amino acids are hydrophilic/lipophilic therefore they have their receptors outside/inside the cells.

Answer 1

hydrophilic; outside

Question 2

Lipophilic hormones have receptors inside/outside of the cell.

Answer 2

inside

Question 3

Tell me the thyroid function pathway.

Answer 3

(blood) dec T3/T4-> (hypothalamus) TRH-> (pituitary) TSH-> (thymus) release T3/T4

Question 4

Tell me the Glycemic control pathway.

Answer 4

Low BS–> glucagon (a-cells in the pancreas)–> liver releases glucose
High BS-> insulin (b-cells released by pancreas)-> fat cells take glucose from blood

Question 5

What are Thionimides? Name a few. MOA? SE?

Answer 5

RX used to decrease hyperthyroidism. Propylthiuracil (PTU), carbiMAZOLE, methiMAZOLE. MOA: inhibits thyroid peroxidase to prevent attachment of iodine into tyrosine. SE: immunosuppressive effects, rash, arthralgias, granulocytopenia, agranulocytosis (see fever, pharyngitis). PTU ok for preg.

Question 6

What is iodine used for? Name agents. It is often combined w/_____ b/c? Response is slow/fast. SE?

Answer 6

hyperthyroid. Potassium iodide solution. Propranolol bc it decreases thyroid storm s/s and inhibits conversion of t4->t3. fast (~24h). Allergic reaction : angio/laryngeal edema

Question 7

Levothyroxine is T3/T4; while Liothyronine is T3/T4. Why is Levothyroxine preferred over Liothyronine? In Levothyroxine you pt’s can/cannot switch btw brands b/c? Which is more potent Levothyroxine or Liothyronine?

Answer 7

T4; T3. Levothyroxine has a longer duration. Cannot b/c they may vary slightly in bioavailability. Liothyronine is 2-3x more potent.

Question 8

Levothyroxine med should increase in___ patients and decrease in____pts.

Answer 8

Pregnancy; elderly

Question 9

Radioactive iodine accumulates in neonate___. Hypothyroidism occurs___.

Answer 9

Thyroid. In 10% of pts the 1st year and then 2-3% q year after that.