Thyroid and Anti-thyroid drugs

Question 1

function Thyroid gland?

Answer 1

• It regulates optimal growth,
  development,
  body temperature
  energy level.

Question 2

Transport of iodide into thyroid gland by

Answer 2

Sodium/Iodide symporter

Question 3

Transport of iodide at the apical membrane is by a transport enzyme

Answer 3

Pendrin

Question 4

Oxidation of iodide to iodine is done at the apical membrane by

Answer 4

thyroidal peroxidase (TPO)

Question 5

T3, T4, MIT, and DIT are released from thyroglobulin by

Answer 5

exocytosis and proteolysis

Question 6

Transport of T3 &T4 in plasma; bound to

Answer 6

thyroxine-binding globulin

Question 7

Metabolism of T4 is by to T3 and rT3

Answer 7

5 deiodinase enzyme

Question 8

Abnormal thyroid stimulation occurs in Grave’s disease by TSH receptor antibody (stimulatory) that results in

Answer 8

thyrotoxicosis and ophthalmopathy

Question 9

Mechanism of action of Thyroid hormones

Answer 9

enters the nucleus (TRa & TRβ)
activates gene transcription
formation of messenger RNA
alteration of protein synthesis

Question 10

Levo thyroxine (T4)

Answer 10

Lack of allergens
Drug of choice

Question 11

Lio thyronine (T3)

Answer 11

Greater cardio-toxicity
Used for short-term suppression of TSH

Question 12

Desiccated thyroid

Answer 12

Protein antigenicity ↑

Question 13

Liotrix

Answer 13

(T4:T3)= (4:1)

Question 14

Clinical Uses of hyperthyroidism drugs

Answer 14

 Loss of thyroid cells (Hypothyroidism)
◦ thyroid surgery
◦ radioactive iodine treatment
 Iodine deficiency (endemic goitre)
 Congenital hypothyroidism
 Hashimoto’s thyroiditis (autoimmune destruction)

Question 15

Adverse effects of hyperthyroidism drugs

Answer 15

Early stage= angina, MI, arrhythmias
Later stage= hyperthyroidism

Question 16

Causes of Hyperthyroidism

Answer 16

1. Grave’s disease
2. goiter
3. Sub-acute thyroiditis; viral infection

Question 17

Drugs treatment of hyperthyroidism

Answer 17

1- Thioamides
2- Iodide salts/ Iodine
3- Radioactive iodine (131I)
4- B-adrenoceptor antagonists

Question 18

(Thioamides) Propylthiouracil (PTU)

Answer 18

used in pregnancy because highly protein-bound

Question 19

T or F (Thioamides) Methimazole is 10 times more potent than PTU

Answer 19

T

Question 20

Mechanism of action of Thioamides

Answer 20

 Inhibit thyroid peroxidase
 Block iodine organification
 Block coupling of iodo-tyrosine residues
 PTU inhibit peripheral conversion of T4→T3

Question 21

Adverse effects of Thioamides

Answer 21

agranulocytosis
Hepatitis (PTU) that can be fatal, and cholestatic jaundice (MTZ).
maculopapular rash

Question 22

Methimazole is preferred over PTU because it has a

Answer 22

longer half-life and a lower incidence of adverse effects

Question 23

Iodide salts/Iodine

Answer 23

• Lugol’s solution (iodine and potassium iodide)
• Saturated solution of potassium iodide.

Question 24

Clinical Uses of Iodide salts/Iodine

Answer 24

1- thyroidectomy
2- severe hyperthyroidism

Question 24

Mechanism of action of Iodide salts/Iodine

Answer 24

(inhibit thyroglobulin proteolysis)
inhibit iodide organification
decrease the size, vascularity, and fragility of the thyroid gland

Question 25

Adverse effects of Iodide salts/Iodine

Answer 25

Iodism: acne-form rash, swollen salivary glands, mucous membrane
ulcerations, conjunctivitis, metallic taste, rhinorrhea, bleeding disorder and drug fever.

Question 26

Reasons for limited use of Iodide salts/Iodine

Answer 26

• increases thyroid stores of iodine
• prevent the use of radioactive iodine
• thyrotoxicosis
• cross placenta

Question 27

Clinical uses of Radioactive Iodine - 131

Answer 27

Thyrotoxicosis & thyroid carcinoma

Question 28

Disadvantages (ADR) Radioactive Iodine - 131

Answer 28

Since it crosses the placenta it is contraindicated during pregnancy and lactation