thyroid

Question 1

1st line tx for Hyperthyroidism

Answer 1

Radioactive Iodine - 131I

Question 2

MoA of Radioactive Iodine

Answer 2

It destroys the thyroid gland through a cytotoxic effect (medaited by B cells)

Question 3

131 I destorys the thyroid gland through a cytotoxic effect , mediated by B cells. this is Restricted to cells of the ———–

Answer 3

Thyroid follicles

Question 4

Amdinistration route of Radioactive iodine

Answer 4

Oral

Question 5

Radioactive Iodine effects seen after ——— and maximal effects ———

Answer 5

1-2 months, max effects 2 months later

Question 6

Adverse effects of Radioactive iodine

Answer 6

Hypothyroidism

Question 7

Can Radioactive iodine be given to pregnant women and children?

Answer 7

Best Avoided

Question 8

Thioureylenes examples

Answer 8

Carbimazole,
methimazole (active metabolite of carbimazole), propylthiouracil - PTU

Question 9

MoA of Carbimazole

Answer 9

competitively inhibit the thyroperoxidase catalysed oxidation reactions

Note:
thryoid peroxidase fxn:
–> Coupling, organification of iodine, oxidation of iodine and thyroglobulin

Question 10

Clinical response of Thioureylenes may take ——-

Answer 10

several weeks

Question 11

Which Thioureylenes is preferred in the tx of hyperthyroidism

Answer 11

Methimazole –> except during the the 1st trimester of pregenancy
* in this case we give Prophylthiouracil

Question 12

You have a pregenant women in her first trimester w/ Hyperthyroidism. What drug will you administer?

Answer 12

Propylthiouracil during the 1st trimester, then switched to Methimazole in the 2nd trimester

Question 13

Why is Propylthiouracil preferred in pregenancy during the 1st trimester over Methimazole?

Answer 13

Methimazole is teratogenic (aplasia cutis) during the 1st trimester

Question 14

MoA of Propylthiouracil

Answer 14

Reduces Deiodination of thyroxin (T4) in peripheral tissues
* (5’ deiodinase inhibition)

* Thioureylene

Question 15

AE of Prophylthiouracil

Answer 15

Hepatotoxicity
BUT safer in pregenacy (1st tri)

Question 16

which drug acts more rapidly Methimazole or Propylthiouracil

Answer 16

Propylthiouracil

Question 17

AE of Thioureylenes

Answer 17

1) Rashes
2) Headache
3) nausea
4) Jaundice
5) Neutroepnia and Agranulocytosis(Rare but fatal)
* therefore, monitor WBC

Question 18

What fatal AE do Thioureyelenes cause

Answer 18

Neutropenia and agranulocytosis

Question 19

Clinical name for Iodine?

Answer 19

Lugol’s Iodine

Question 20

Clinical uses of Lugol’s Iodine

Answer 20

• Preparation for thyroidectomy
• As part of the treatment of severe thyrotoxic crisis (thyroid storm)

Question 21

For how many days, prior to a thyroidectomy, should a pateint be taking Lugol’s iodine to attain maximal pharmacological effects?

Answer 21

10-15 days

Question 22

AE of Lugol’s Iodine

Answer 22

1) Allergic rxn
2) Lacrimation
3) Conjuctivitis
4) pain in the Salivary gland
5) Cold-like syndrome

Question 23

Which drug causes the following side effects: lacrimation, conjuctivities, pain in the salivary glands, headaches and congestion ?

Answer 23

Lugol’s Iodine

Question 24

Administration of Lugol’s Iodine

Answer 24

Oral in a soulution w/ potassium iodide

Question 25

Lugol's Iodine temporarily inhibites the release of --------------- homrones

Answer 25

Thyroid (TH)

Question 26

MoA of Lugol's Iodine

Answer 26

* Converted to Iodide (I-) in vivo * Temporarily inhibits the release of TH --> marked **reduction of vascularity and size of gland**

Question 27

What drug can you administer to reduce signs and symptoms of Hyperthyroidism (Tachycardia, dysrhythmias, tremor, agitation)?

Answer 27

Beta-blockers

Question 28

Clinical uses of Beta -blockers in the tx of Hyperthyroidism

Answer 28

1) decreases signs and symptoms of hyperthyroidism 2) Acute Hyperthyroid crisis (thyroid storm) 3) Preperation of thyrotoxic patients for surgery

Question 29

55 yr women w/ Grave's disease , upon examination Exopthalmos was evident. tx with an eyedrop is recomended. what drug is appropriate to admisinister to this patient?

Answer 29

Guanethidine (Eye drops)

Question 30

MoA of Guanethidine

Answer 30

* Noradrenergic-blocking agent * Relaxes smooth muscle that causes eyelid retraction

Question 31

1st line tx in Hypothyroidism

Answer 31

T4 analouge - **Levothyroxine**

Question 32

Why do we administer T4 analouges insteade of T3 analouges in Hypothyroidism tx?

Answer 32

T3 analouge -**Liothyronine** are given for acute emergencies

Question 33

Administration route of Liothyronine

Answer 33

IV (emergency) | * T3 Analouge

Question 34

Administration route of Levothyroxine

Answer 34

Oral formualtion | * T4 Analogue

Question 35

clinical uses of Liothyronine

Answer 35

**Acute Hypothyroidism emergencies** * Short duration of axn (faster onset)

Question 36

Which has a faster-onset , Liothyronine or Levothyroxine?

Answer 36

Liothyronine (T3 Analogue)

Question 37

Iodine deficieny in Hypothyroidism is treated w?

Answer 37

Iodide

Question 38

Example of Hypothyrodism disease

Answer 38

Hashimoto thyroditis

Question 39

What are Thyroid replacement therapies?

Answer 39

* Levothyroxine (T4 Analogue) * Liothyronine (T3 Analogue)

Question 40

AE of Replacement therapy (Liothyronine, Levothyroxine)

Answer 40

* Hyperthyroidism * Tremors * Heat intolerance * Angina pectoris * Cardiac dysrhythmias * Cardiac failure * Increased bone resorption -Osteoporosis

Question 41

Drugs that may affect thyroid function

Answer 41

**1) *Amiodarone*** - Rich in iodine - Can cause hyperthyroidism or hypothyroidism **2) Iodine-containing radiocontrast agents drugs** - Iopanoic acid - Hypothyroidism **3) Sulfonamides** - E.g. sulfonyureas - Hypothyroidism **4) Lithium** - Hypothyroidism

Question 42

Drugs that reduce TSH release

Answer 42

Somatostatin (aka Growth hormone inhibitor hormone)

Question 43

# ** Drugs used for Thyroid strom tx?

Answer 43

1) Lugol's iodine 2) Beta-blockers 3) Glucocorticoids 4) PTU