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Y2S1-Pharmacology > Drugs used in the treatment of thyroid diseases > Flashcards

Drugs used in the treatment of thyroid diseases Flashcards

1
Q

Which body cells directly intake iodide ions?

A

Only the thyroid cells, as they have the symporter

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2
Q

What are the main pharmacological targets to inhibit the formation of thyroxine?

A

1) “MAINLY” Target the peroxidase enzyme, which is responsible for the iodination and coupling of the tyrosine residues (via drugs called thioamide drugs)

2) Inhibit the uptake of iodide by giving a high saturation of potassium iodide

3) Lithium, a bipolar drug can also be used in hyperthyroidism

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3
Q

What does Anti-TPO indicate if detected in the tests?

A

That the peroxidase enzyme is getting attacked resulting in a decreased production of the thyroid hormone = hypothyroidism

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4
Q

What does Anti-TGAb indicate in the blood?

A

There are enzymes against thyroglobulins which also means that there is less thyroid hormone being synthesized and thus hypothyroidism

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5
Q

What does anti-TSI indicate in the blood?

A

There is an antibody that overstimulates the thyroid gland which could mean excess thyroid hormone and thus hyperthyroidism

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6
Q

What is the relationship between TSH and FT4 (Free thyroid hormone)?

A

Inverse relationship

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7
Q

What is the normal range of TSH?

A

0.4-4.5 mIU/L

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8
Q

What are the drugs that affects the secretion of TSH?

A

1) Decreases TSH:

  • D2-receptor agonists (Dopamine, Dobutamine, levodopa, cabergoline, bromocriptine)
  • Octreotide (AKA GHIH)
  • Glucocorticoids
  • Metformin

2) Increases TSH secretion:

  • D2-receptor antagonists (Metoclopramide and domperidone)
  • These are the side effects of those drugs
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9
Q

What is the non-pharmacological therapy of hyperthyroidism?

A

Surgery, when the thyroid gets enlarged, with severe ophthalmopathy, and there is a lack of remission using antithyroid drugs

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10
Q

What are the drugs used in the preparation for thyroidectomy?

A

1) Thionamides

  • Reduces the synthesis of thyroid hormone

2) Beta-blockers

  • Inhibits T3 production preventing arrhythmias

3) Supersaturated iodine

  • Reduces gland vascularity via the Wolff-chaikoff effect

4) Lithium carbonate

  • Alternative for patients not responding to iodine or thionamides blocking the release of thyroid hormone

5) Dexamethasone

  • Reduces the levels of TSH and inhibits the deionization of T4
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11
Q

What are the different classes of pharmacological therapies for hyperthyroidism?

A

1) Antithyroid medications

2) Iodides

3) Adrenergic blockers

4) Radioactive iodine

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12
Q

What are the antithyroid medications?

A

1) Methimazole

2) Propylothiouracil

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13
Q

What is the mechanism of action of methimazole (MMI)?

A

It inhibits the coupling of MIT and DIT to T4 & T3

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14
Q

What is the mechanism of action of propylthiouracil (PTU)?

A
  • They inhibit the coupling of MIT and DIT to T3 & T4
  • It also inhibits the peripheral conversion of T4 to T3 (prevents activation in peripheral tissue)
  • More effective, (propylthiouracil acts peripherally and it’s the drug of choice for pregnant women)
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15
Q

What are the adverse effects of antithyroid medications?

A

1) Congenital malformation (with Methimazole)

2) Agranulocytosis (severe reduction in the number of granulocytes)

Transient

3) Arthralgias

4) Pruritic maculopapular rashes

5) Fevers

6) Hepatotoxicity (not transient)

7) Benign transient leukopenia

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16
Q

What is the mechanism of action of iodides?

A

1) It acutely blocks the release of thyroid hormone

2) It inhibits the thyroid hormone biosynthesis

3) It decreases the size of the gland

  • helpful especially in goiters to decrease the size of the gland before surgery
  • However, in large doses, it might exacerbate hyperthyroidism
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17
Q

When is the use of iodides contraindicated?

A

In multinodular goiters

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18
Q

What is meant by the wolff-chaikoff effect?

A
  • Temporary reduction in thyroid hormone synthesis due to high levels of iodine that is introduced, as the body will inhibit hormone production via peroxidase, to avoid the excess buildup of iodine
  • This mechanism is used clinically to reduce thyroid hormone levels before thyroid surgery
19
Q

What are the side effects of iodides?

A
  • SIGH

1) Swelling of the Salivary gland

2) Iodism (burning of mouth/throat + severe headache)

3) Gynecomastia

4) Hypersensitivity

20
Q

Which drug is used in graves disease?

A

Radioactive iodine I(131)

  • This drug is ideal if no surgery is being done, very effective
21
Q

Which drug is used in toxic autonomous nodules (toxic adenomas) and toxic multinodular goiter?

A
  • Toxic autonomous nodules (also called toxic adenomas) are thyroid nodules that function independently of the normal regulatory mechanisms of the thyroid gland (they are not regulated by TSH release!). This condition obviously causes excess thyroid hormone or hyperthyroidism even without TSH being released by the anterior pituitary
  • Radioactive Iodine (131), we can use potassium iodide in conjugation
22
Q

When is radioactive iodine contraindicated?

A

PREGNANCY

23
Q

Which drug is given prior to radioactive iodine in elderly and CVD patients?

A

Thioamides

24
Q

Why is radioactive iodine ideal?

A

Because it can only be absorbed by the thyroid gland, and thus its effects are localized

25
Q

When is potassium iodide oral solution indicated?

A

Prior to surgery to suppress the release of T3 and T4

26
Q

Why do we give adrenergic blockers in hyperthyroidism or thyrotoxicosis?

A
  • Due to the increased Heart rate and stress
  • It will also Ameliorate thyrotoxic symptoms
  • It is used as adjunctive therapy with antithyroid drugs, RAI, or iodides
27
Q

Which BB is used in thyrotoxicosis?

A
  • Non-selective ones like propranolol
28
Q

Which drug is used in the case of graves in a pregnant woman?

A
  • Propylthiouracil (during the first trimester)
  • If not pregnancy we can use the antithyroid (MMI & PTU) medications starting with a high dose and then decreasing it
29
Q

What is the first-line drug in the treatment of neonatal and pediatric hyperthyroidism?

A

Methimazole

  • kids can’t say “messi” ⚽ , they say methi…. (methi)mazole
  • If not then Propylthiouracil
30
Q

What is a thyroid storm?

A
  • A life-threatening medical emergency
  • It could be a result of infection, trauma, surgery, withdrawal from antithyroid medications
  • T4 levels increase rapidly in the blood and must be managed quickly.
31
Q

What therapeutic measures should be considered in case of a thyroid storm?

A

1) Suppression of thyroid hormone formation and release

2) Antiadrenergic therapy

3) Administration of corticosteroids

4) Treating the complications

32
Q

What is the first-line treatment in case of a thyroid storm?

A

Propylthiouracil

33
Q

How to manage a thyroid stomr?

A

Ninja Nerd summarizes the management for thyroid storm with the 6 Ps:

1) Propranolol (antiadrenergic drug, a beta blocker) -> slows down fast heart rate, short-acting

2) Propylthiouracil (PTU) -> thioamide, decreases thyroid hormone levels

3) Prednisone (corticosteroids) -> reduces inflammation, and also prevents conversion of T4->T3. Helps with adrenal insufficiency

4) Potassium Iodide -> inhibits the release of thyroid hormones

5) Plenty of fluids -> maintain electrolytes

6) Panadol/ pyretic control -> reduce fever

34
Q

Which drug is used for the exophthalmos of graves disease?

A

Teprotumumab

35
Q

What is teprotumumab?

A

Human monoclonal antibody that binds to IGF-1R in our eyes (Insulin-like growth factor 1, receptor)

  • It only corrects the protrusion, NOT hyperthyroidism
  • TEProtumumab: T-reats E-ye P-rotrusion
36
Q

What are the drugs for hypothyroidism?

A

1) Levothyroxine

  • Drug of choice (chemically stable, inexpensive, uniform potency)

2) Liothyronine

  • (It has a higher risk of CVS effects, high cost, difficult to monitor)

3) Liotrix

  • Expensive, but it is stable, and pure
37
Q

What is myxedema?

A

First, in hypothyroidism, the skin becomes coarse, dry, and cold, eventually, hypothyroidism might cause myxedema (described as a dry waxy swelling of the skin with edema)

38
Q

What is meant by myxedema coma?

A
  • Emergency opposite to the thyroid storm, Characterized by hypothermia, hypoglycemia, weakness, altered sensory perception and shock, the end stage of long-standing untreated hypothyroidism
39
Q

Which drug is given for a long-standing hypothyroidism?

A

Thyroxine

40
Q

What is the most common cause of hypothyroidism in adults?

A

Hashimoto disease

  • Other things can include thyroid surgery, dietary iodine insufficiency, thyroid hyperplasia, or enzymatic defects
41
Q

How to manage hypothyroidism?

A

Replacement therapy with a thyroid hormone preparation

42
Q

What is the initial treatment of myxedema coma?

A

1) IV bolus Levothyroxine

  • Patients with myxedema coma can have concomitant primary adrenal insufficiency, while patients with secondary hypothyroidism may have associated secondary adrenal insufficiency
  • IV hydrocortisone should be given until coexisting adrenal suppression is ruled out
43
Q

Which drug is given in congenital hypothyroidism?

A

Levothyroxine

  • Could be due to radioactive iodine in pregnant ladies
44
Q

What is the drug of choice for hypothyroidism in pregnancy?

A

Levothyroxine

Y2S1-Pharmacology (10 decks)

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