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MS 2 - Unit 5 > "Pharmacology Thyroid Ying Huang" > Flashcards

"Pharmacology Thyroid Ying Huang" Flashcards

1
Q

What enzymes convert T4 to T3?

A

D1 and D2 deiodinases
D1 - liver and kidney
D2 - CNS, pituitary gland, thyroid, heart, brown adipose tissue, skeletal muscle

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2
Q

What is D3?

A

D3 deiodinase - predominantly in brain and skin and placenta

Inactivates T3 to T2

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3
Q

What is the cause of congenital hypothyroidism?

A

Mutations in the sodium-iodide symporter gene affecting iodide transport

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4
Q

What causes Hashimoto’s thyroiditis?

A

Autoantibodies attack the sodium-iodide symporter and cause hypothyroidism

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5
Q

Hyperthyroidism has what levels of TSH and T4?

A

Hyperthyroidism:
Low TSH
High T4

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6
Q

Primary hypothyroidism has what levels of TSH and T4?

A

Primary hypothyroidism:
High TSH
Low T4

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7
Q

Secondary hypothyroidism has what levels of TSH and T4?

A

Secondary hypothyroidism:
Low TSH
Low T4

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8
Q

What are common causes of hypothyroidism?

A 
Hashimoto's
Iodine deficiency
Thyroid ablation
Secondary hypothyroidism (pituitary disorder, hypothalamic disorder such as adenoma or radiotherapy)
Myxedema
Cretinism
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9
Q

Class: Levothyroxine

A

Synthetic thyroid hormone (T4)

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10
Q

MOA: Levothyroxine

A

Converted to T3 in liver; T3 binds to TR complex to influence gene expression
Half life of 6-7 days

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11
Q

Uses: Levothyroxine

A

Drug of choice for hypothyroidism (longer half-life than T3)

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12
Q

Side effects: Levothyroxine

A

Hyperthyroidism: heart palpitations, nervousness, shaking, heat intolerance, weight loss

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13
Q

Class: Liothyronine

A

Synthetic thyroid hormone (T3)

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14
Q

MOA: Liothyronine

A

T3 binds to TR complex in nucleus to influence gene expression
Half life of 1 day

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15
Q

Uses: Liothyronine

A

Acute management of hypothyroidism (rapid effect); myxedema coma (IV formulation)

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16
Q

Side effects: Liothyronine

A

Hyperthyroidism: heart palpitations, nervousness, shaking, heat intolerance, weight loss

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17
Q

Class: Liotrix

A

Synthetic thyroid hormone (T4 & T3)

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18
Q

MOA: Liotrix

A

Converted to T3 in liver; T3 binds toTR complex to influence gene expression

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19
Q

Uses: Liotrix

A

Thyroid hormone replacement therapy (4:1 mix of T4:T3; not used much)

20
Q

Side effects: Liotrix

A

Hyperthyroidism: heart palpitations, nervousness, shaking, heat intolerance, weight loss

21
Q

Levothyroxine is not indicated in patients with:

A

Chronic Fatigue Syndrome bc they have difficulty converting T4 to T3
Use Liothyronine in these patients

22
Q

What is the drug of choice for acute hypothyroidism, such as myxedema coma?

A

IV formulation of Liothyronine

23
Q

What causes Grave’s disease?

A

Thyroid-stimulating antibodies which bind to and activate the thyrotropin receptor on thyroid cells

The second most common cause of hyperthyroidism is nodular goiter (older age group). Other causes include thyroiditis or thyroid cancer.

24
Q

Why would a beta blocker such as propranolol be indicated for hyperthyroidism?

A

It would dampen the sympathetic effects of the hyperthyroid function

25
Q

Class: Propylthiouracil

A

Thioamide (thyroid peroxidase inhibitors)

26
Q

MOA: Propylthiouracil

A

Inhibit organification of iodide and coupling of iodotyrosine; also reduces peripheral deiodination of T4 to T3 by D1

27
Q

Uses: Propylthiouracil

A

Hyperthyroidism; thyrotoxicosis (high dose); drug of choice for hyperthyroidism during pregnancy

28
Q

Side effects: Propylthiouracil

A

Rare side effects: hepatitis, agranulocytosis (higher than methimazole), lupus-like syndrome

29
Q

Class: Methimazole

A

Thioamide (thyroid peroxidase inhibitors)

30
Q

MOA: Methimazole

A

Inhibit organification of iodide and coupling of iodotyrosine; active metabolite of carbimazole; less effect on T4 to T3 conversion

31
Q

Uses: Methimazole

A

Hyperthyroidism; thyrotoxicosis (high dose)

32
Q

Side effects: Methimazole

A

Rare side effects: hepatitis, agranulocytosis (less than propylthiouracil), lupus-like syndrome

33
Q

Class: Carbimazole

A

Thioamide (thyroid peroxidase inhibitors)

34
Q

MOA: Carbimazole

A

Prodrug converted to methimazole; Inhibits organification of iodide and coupling of iodotyrosine; less effect on T4 to T3 conversion

35
Q

Uses: Carbimazole

A

Hyperthyroidism; thyrotoxicosis (high dose)

36
Q

Side effects: Carbimazole

A

Rare side effects: hepatitis, agranulocytosis, lupus-like syndrome

37
Q

In thyrotoxicosis, what route of administration may be necessary?

A

Rectal

38
Q

Which antithyroid drug has a higher risk of agranulocytosis, propylthiouracil or methimazole?

A

Propylthiouracil

39
Q

Propylthiouracil is the preferred antithyroid drug in what patient population?

A

Pregnant and breast-feeding patients

40
Q

Patients taking an anti-thyroid who develop agranulocytosis are then candidates for what therapies?

A

Radioactive iodine or surgery

41
Q

Class: Radioactive Iodine

A

Radioactive isotope

42
Q

MOA: Radioactive Iodine

A

Radioactive agent that emits beta particles and gamma rays that destroy thyroid cells

43
Q

Uses: Radioactive Iodine

A

Treatment of choice for hyperthyroidism after antithyroid drug therapy; ablation after cancer

44
Q

Side effects: Radioactive Iodine

A

Transient or permanent hypothyroidism; increases cancer risk

45
Q

Radioactive iodine is contraindicated in what patient population?

A

Pregnant and breastfeeding patients

MS 2 - Unit 5 (21 decks)

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