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Pharmacology 2nd Sem Midterm > Thyroid And Antithyroid Agents > Flashcards

Thyroid And Antithyroid Agents Flashcards

1
Q

Thyroid hormones essential for

A

Growth and development

Regulation of energy metabolism

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2
Q

Synthesis of thyroid hormone dependent on

A

Dietary iodine 150-200 ug

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3
Q

Major steps on synthesis of thyroid hormone

A 
Iodine trapping
Oxidation of iodine 
Iodination of tyrosine
Formation of T3 and T4
Secretion 
Peripheral conversion of T4 to T3
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4
Q

Ingested iodine is converted to iodide and absorbed in the GIT.
Principal organs involved

A

Thyroid - for hormone synthesis
Kidney- for secretion
Liver- for metabolism

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5
Q

Is the active transport of iodide from circulation to colloid of thyroid gland
Iodide pump

A

Iodide trapping

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6
Q

Iodide trapping is stimulated by

A

Thyrotropin

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7
Q

Iodide trapping is inhibited by

A

Thiocyanate

Perchlorate

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8
Q

Oxidation/Iodination

Iodide is oxidized to iodine by

A

Thyroid peroxidase

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9
Q

Oxidation/Iodination

Results

A

Mono iodo tyrosyl

Diiodotyrosyl

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10
Q

Formation of T3 and T4

A

Coupling reaction

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11
Q

MIT + DIT = T3 or triiodothyronine

DIT + DIT = T4 thyroxine

A

T3 is 3-5x more active than T4

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12
Q

T3 and T4 are synthesized and stored in the

A

Thyroglobulin

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13
Q

Secretion of T3 and T4 is initiated by

A

Endocytosis

Exit the cell by exocytosis

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14
Q

Peripheral conversion of T4 and T3

Normal daily production

A

T4- 70-90 ug

T3- 15-30 ug

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15
Q

Enzyme involved in conversion of t4 to t3

A

5 deiodinase

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16
Q

Transport of thyroid hormone in the blood

T3 and T4 bound in

A

Thyroxin binding globulin TBG

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17
Q

Total t4 free

Total t3 free

A
  1. 03%

0. 2-0.5%

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18
Q

Only free form is active

A

T3 is less firmly bound

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19
Q

Causes increase TBG with increase binding thus decrease in free form

A

Pregnancy and estrogen

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20
Q

Half life

A

T3 - 2days or less

T4 - 6-7 days

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21
Q

Half life in hyperthyroidism and hypothyroidism

A

Hyper- decreased to 3-4 days

Hypo- increased to 9-10 days

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22
Q

Marine life sea fish / shells

A

200-1000 ug/kg

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23
Q

5kg of veg/fruits
Or
3kgof meat or fresh water fish

A

100 ug iodine

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24
Q

1 gram of iodized salt

A

100ug iodine

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25
Q

2 forms of hyperthyroidism

A

Diffuse (grave dis. )
- dalagang malaking mata, may edema, bagsak ang resestensya. IgG

Nodular toxic goiter (plummer’s disease)
- maganda na may goiter

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26
Q

Thyroid Hormone

Synthetic

A

Levothyroxine
Liothyronin
Liotrix

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27
Q

Thyroid Hormone

Natural (pig)

A

Desiccated thyroid

Thyroglobulin

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28
Q

Preparation of choice for replacement therapy for hypothyroidism and suppression therapy

A

Levothyroxine

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29
Q

Levothyroxine

Characteristics 1

A

Stability
Content uniformity
Low cost

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30
Q

Levothyroxine

Characteristics 2

A

Lack of allergy
Easy interpretation
Long half life

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31
Q

Levothyroxine

Preparation

A

Synthroid
Levothroid

Eltroxin - availe in the Philippines

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32
Q

Best used as a diagnostic test in T3 suppression and short term suppression of TSH

A

Liothyronine

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33
Q

Liothyronine

Halos kabaliktaran ng levothyroxine in terms ng characteristics

A

Short half life (24hours)

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34
Q

More cardio toxic

A

Liothyronine

35
Q

Liothyronine

Preparation

A

Tertoxin, 20 ug/tab

36
Q

A mixture of levothyroxine and iodothyromide in ratio of 4:1

A

Liotrix

37
Q

Liotix preparation

A

Euthyroid

Thylolar

38
Q

Fine powder from desiccated pig thyroid

A

Thyroid

39
Q

Thyroid preparation

A

Armour

Thyran

40
Q

Purified pig extract

A

Thyroglobulin

41
Q

Thyroglobulin preparation

A

Proloid

42
Q

Actions of thyroid hormone

A 
Regualtion of growth and development
Calorigenic effect
Cardiovascular effect
Metabolic effect
Inhibition of secretion of TSH
43
Q

Antithyroid agents 4 categories

A

Thionamides or thiourylenes
Ionic inhibitors
Iodide
Radioactive iodine

44
Q

Interfere directly with thyroid hormone synthesis

A

Thionamides or thiourylenes

45
Q

Block the iodide transport mechanism

A

Ionic inhibitors

46
Q

Suppression of thyroid hormone synthesis when in high doses

A

Iodine

47
Q

Damages and destroy the gland by ionizing radiation

A

Radioactive iodine

48
Q

Thionamides 2 groups

A

Propylthioracil PTU

Methimazole (tapazole)

49
Q

Rapidly absorbed
Peak serum level after 1 hour
Mostly excreted in the kidneys as the inactive glucoronide within 24 hours

A

Propylthioracil

50
Q

10x more active that PTU

Slower excretion than PTU

A

Methimazole

51
Q

Completely absorbed and accumulate in the thyroid gland

A

Methimazole

52
Q

Mother drug, converted to methimazole in vivo

A

Carbimazole

53
Q

Preferred for pregnant women since it is strongly bound to protein

A

PTU

54
Q

Thionamides

Prevent hormone synthesis by inhibiting the

A

Thyroid peroxidasecatalyzed

55
Q

Blocks coupling of iodo tyrosine but

A

Does not block iodide uptake by the gland

56
Q

Thionamides

Inhibit deiodinase

A

PUT but not methimazole

57
Q

Thionamides

Early toxicity

A

Maculopapular rash, fever

58
Q

Thionamides

Toxicity late

A 
Vasculitis
Hepatitis
Arthralgia
Lymphadenopathy
Lupus like reaction
Polyserositis
59
Q

Thionamides

Most dangerous toxicity

A

Agranulocytosis

Sore with high fever are the signs

60
Q

Blocks uptake of iodine by the gland thru competitive inhibition of iodide transport.

A

Anion inhibitors

61
Q

Anion inhibitors

Agents

A

Perchlorate
Peterchnetate
Thicyanate

62
Q

Anion inhibitors

May produce aplastic anemia

A

Perchlorate

63
Q

Very toxic and use only for diagnostic purposes

A

Anion inhibitors

64
Q

Anion inhibitors

May even block organification of iodine
Produce by plant glycoside like cabbage

A

Thiocyonate

65
Q

Inhibit organification

Inhibits hormone release thru inhibition of thyroglobulin decreased the size and vascularity of the gland

A

Iodides

66
Q

Iodides

Giving >6mg/day rapid improvement in thyrotoxic symptoms within

A

2-7 days

67
Q

Iodides

Disadvantages

A

Delay onset of Thionamides therapy
Prevent use of radioactive iodine therapy
Cross placenta and cause fetal goiter

68
Q

Iodides

Should not be used alone because

A

The gland will escape from the iodide block in 2-8 weeks

69
Q

Iodides

Withdrawals

A

Thyrotoxicosis

Iodoenriched gland

70
Q

Iodides

Toxicity

A

Acneiform
Metallic taste
Anaphylaxis

Conjunctivitis
Rhinorrhea

Drug fever

Swollen salivary glands
Mucous ulcer

71
Q

Important alternative if iodide sa and Thionamides are contraindicated

A

Iodinated contrast media

72
Q

Iodinated contrast media

Agents

A

Ipodate

Lopanoic acid

73
Q

Not approved of FDA

A

Iodinated contrast media

74
Q

Only isotope used for thyrotoxicosis

A

Radioactive iodine

75
Q

Radioactive iodine

In solution as

A

NA 1311

76
Q

Radioactive iodine

A

B rays
5 days half life
400-2000

77
Q

Radioactive iodine

Evidence of thyroid destruction

A

Epithelial swelling and necrosis
Follicular disruption
Edema
Leukocytic infiltration

78
Q

Radioactive iodine

Advantages

A

Easy administration
Effectiveness
Low expense
Absence of pain

79
Q

Radioactive iodine

Disadvantages

A

Genetic damage
Leukemianeoplasia

35 yo and above

80
Q

Radioactive iodine

Contraindication

A

Pregnancy

Nursing mothers

81
Q

Agents that deplete cathecolamines

A

Reserpine

Guanitidine

82
Q

Useful because they impair tissue response at the receptor site

A

Beta blocker (propranolol)

83
Q

Weight of thyroid gland

A

15-20 grams

Pharmacology 2nd Sem Midterm (1 decks)

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