Komiskey 10-30-07 Thyroid And Antithyroid Drugs

Front 1

Reading: Basic and Clinical Pharmacology, Chapter 38, pp 615 - 633, 2007

Back 1

Ok

Front 2

nucleus of HT that releases TRH

Back 2

paraventricular

Front 3

TSH is pulsatilely released from

a) ant. pit
b) post. pit

Back 3

a) ant. pit

Front 4

TRH has a positive feedback effect on pit. SST has what kind of feedback on pit?

Back 4

negative


Somatostatin, a hypothalamic factor known for its inhibitory effect on growth hormone secretion, was demonstrated to blunt the TSH response to TRH and CRH.

Front 5

More potent

T4
T3

Back 5

T3

Front 6

Which ismore protein bound?

T3
T4

Back 6

T4

Front 7

Which is more "free"

T3
T4

Back 7

T3

Front 8

Which is attracted more to TBPA
T3
T4?

Back 8

T4

Front 9

Drugs such as ipodate, B-blockers, and corticosteroids, and severe illness or starvation inhibit the 5’-deiodinase necessary for the conversion of T4 to T3, resulting in low T3 and high ___ levels in the serum.

Back 9

rT3

Front 10

What condition is Named for characteristic thickening of subcutaneous tissue caused by deposition of mucopolysaccharides
Once thought to be due to increased mucus ("myx") formation

Back 10

Myxedema

Front 11

Agents for thyroid replacement

Back 11

levothyroxine - synthetic T4
liothyronine - synthetic T3
liotrix - mixture of T4 and T3

Front 12

the preferred thyroid hormone for use in the treatment of hypothyroidism because of the absence of variability and the ease of monitoring of plasma concentrations; it is the drug of choice in the treatment of congenital hypothyroidism

Back 12

Levothyroxine

Front 13

(T4)-drug of choice.

Back 13

Levothyroxine sodium

Front 14

L-T4 is given once daily because of long half life (goal: keep ____ in normal
range) Steady state is achieved at 6-8 weeks.

Back 14

TSH

Front 15

recommended by some clinicians because of its
short half-life
reversible effects for initial therapy in myxedema and myxedema coma, as well as for hypothyroid patients who also have heart disease, although there are significant risks associated with the latter use

Back 15

Liothyronine

Front 16

may also be preferred during preparation for radioisotope scanning procedures or when gastrointestinal absorption processes are impaired.

Back 16

Liothyronine

Front 17

Time to peak therapeutic effect oral dosing:
Levothyroxine, thyroglobulin, thyroid:
Liothyronine:

Back 17

Levothyroxine, thyroglobulin, thyroid: 3 to 4 weeks.

Liothyronine: 48 to 72 hours

Front 18

treatment of Myxedema coma

Back 18

i.v. levothyroxine
200 to 300 µg initially
to saturate binding proteins
Maintenance: 50 µg/day
Liothyronine for more rapid effect

Front 19

Acute massive T4/T3 overdose is treated by

Back 19

reducing gastrointestinal absorption, if possible, by means of vomiting, followed by emptying of the stomach and/or use of a charcoal instillation, which may be useful up to 3 to 4 hours after oral ingestion of toxic doses of thyroid hormones.

Front 20

Overdose treatment if congestive heart failure develops

Back 20

Cardiac glycosides

Front 21

treatment of increased sympathetic activity.

Back 21

Beta-adrenergic blocking agents such as propranolol

Front 22

to partially inhibit conversion of T 4 to T 3
???????????????

Back 22

Intravenous hydrocortisone

Front 23

Levothyroxine Malabsorption Syndromes

Back 23

Postjejunoileal bypass surgery
Short bowel syndrome
Celiac disease

Front 24

Reduced Levothyroxine Absorption

Back 24

Colestipol hydrochloride
Sucralfate
Ferrous sulfate
Food (eg, soybean formula)
Aluminum hydroxide
Cholestyramine
Sodium polystyrene sulfonate

Front 25

Agents increasing TBG levels

Back 25

Estrogens Tamoxifen
Methadone Clofibrate
5-Fluorouracil Heroin

Front 26

Agents decreasing TBG levels

Back 26

Androgens Corticosteroids

Front 27

Agents interfering with TBG binding

Back 27

Phenytoin Carbamazepine
Salicylates Phenylbutazone
Diazepam

Front 28

Agents interfering with TBPA binding

Back 28

Salicylates

Front 29

Drugs that induce cytochrome P450 enzymes, increase T4 glucuronidation and clearance

Back 29

phenytoin
carbamazepine

Front 30

Over-replacement : what does TSH look like?

Back 30

down

TSH <0.5 microIU/mL

Front 31

Agents for treatment of hyperthyroid states

Back 31

Thioamides: Propylthiouracil (PTU), Methimazole*****
Radioactive iodine
Sodium or potassium iodide

Front 32

Anti Thyroid MOA

Back 32

Inhibits hormone biosynthetic iodination and T4 deiodination enzyme 5’-deiodinase I, prevents “coupling” of two diiodotyrosines during synthesis

Front 33

Adverse reactions to anti-thyroid in <1% of patients:
What is the most severe side effect possible---watch for signs of sore throat or fever

Back 33

Agranulocytosis

Front 34

PTU blocks deiodinase D1 in peripheral tissues;
Does methimazole do this also?

Back 34

methimazole does not

Front 35

Adverse effects of Anti-thyroid drugs

Back 35

agranulocytosis (reversible)
rash (most common)
edema.

Front 36

what is DOC?

Back 36

methimazole

Front 37

______ indicated for hyperthyroidism during pregnancy

Back 37

Propylthiouracil

Front 38

also partially inhibits T4 to T3
May be used when fast action is desired

Back 38

Propylthiouracil (PTU):

Front 39

Is Protein binding significant with Methimazole?

Back 39

no

Front 40

if agranulocytosis, thrombocytopenia, or hepatic dysfunction occurs, is substitution with another thioamide recommended ?

Back 40

no

Front 41

Propylthiouracil is generally preferred over methimazole during lactation because methimazole is distributed into _____ more readily (approximately ten-fold), presumably due to its insignificant level of protein binding and ionization

Back 41

breast milk

Front 42

Treatment of thyroid storm or thyrotoxic crisis

Back 42

1. Propranolol blunts sympathetic stimulation that occurs in hyperthyroidism.

2. Potassium iodide inhibits thyroid hormone release.

3. Large doses of propylthiouracil

Front 43

Blockade of Hormone Release
Is iodide useful for long term therapy?

Back 43

no

Front 44

Radioactive Iodine :
______ particles act on parenchymal cells with little damage to surrounding tissue

Back 44

Beta

Front 45

Chief disadvantages of Radioactive Iodine are

Back 45

high incidence of delayed hypothyroidism

Front 46

Main contraindication of Radioactive Iodine is ______

Back 46

pregnancy

Front 47

Most common treatment in U.S

Back 47

Radioactive Iodine (131I)

Front 48

For thyroid protection against nuclear fallout, what did polish children take?

Back 48

KI