Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Pharmacology > ERS L14 - Thyroid Disorders: Pharmacological Agents > Flashcards

ERS L14 - Thyroid Disorders: Pharmacological Agents Flashcards

1
Q

Causes of hypothyroidism

A
  1. Hypopituitarism
  2. Congenital disease, e.g. cretinism (poor development of thyroid gland)
  3. Hashimoto’s thyroiditis
  4. Goitrogens e.g. cabbage
  5. Medical treatment (including drugs e.g. lithium)
  6. Dietary insufficiency of iodine
  7. Excess iodine (Wolff-Chaikoff effect) (but with escape mechanism in adults)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Treat hypothyroid coma

A

Liothyronine (T3)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Routine replacement therapy for hypothyroidism

A

Thyroxine (T4)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Liothyronine

A

T3
For severe and acute hypothyroidism, e.g. hypothyroid coma (very low CO, life-threatening)

Quicker effect:
more active, less protein-bound

Higher rate of clearance than thyroxine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Side effects of liothyronine / thyroxine

A
  1. Thyrotoxicosis
  2. Risk of worsening ischemic symptoms (Caution in patients with cardiovascular disorder)
  3. Risk of acute adrenal crisis (Thyroxine increases metabolic clearance of adrenocortical hormones)

Close monitoring of serum T4 and TSH
(overdose: low TSH, high T4)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

When giving thyroid hormone replacement, what to take note of?

A

Any CV disorders?
(Can worsen ischaemic symptoms)

Any adrenal insufficiency?
(Risk of acute adrenal crisis)

Risk of thyrotoxicosis

Close monitoring of TSH and T4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Causes of hyperthyroidism

A
  1. Graves’ disease
  2. Adenoma
  3. Drugs, e.g. amiodarone
  4. (Pregnancy)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Short-term treatment for hyperthyroidism

A

Beta-blocker
Beta-blocker + Lugol’s solution

Indications:

  1. Thyrotoxic crisis (thyroid storm)
  2. Before surgery (Faster recovery + reduce bleeding during surgery by Lugol’s solution)
  3. Initial treatment while long-term treatment are taking effect
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Long-term treatment for hyperthyroidism

A

Thionamides: carbimazole, methimazole, propylthiouracil

Radioiodine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

MoA of Lugol’s solution

A

5% I2 + 10% KI

  1. Inhibit H2O2 generation: Inhibit organification (iodination of tyrosine residues of thyroglobulin)
  2. Inhibit release of T3 and T4
  3. Decrease size and vascularity of hyperplastic thyroid gland –> Reduce risk of bleeding during surgery
  • 0.1-0.3mL,well-diluted with water or milk, 3 times/day
  • Rapid onset: improve symptoms in 2-7 days
  • Use pre-operatively
  • Therapy usually for 10-14 days only: desensitization afterwards
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why isn’t Lugol’s solution used for long-term treatment?

A

Desensitization: downregulation of Na/I symporter –> ineffective after ~2 weeks
(Therapy usually for 10-14 days only)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Side effects of Lugol’s solution

A

Allergy:

  1. Fever
  2. Rash
  3. Conjunctivitis
  4. Angioedema
  5. Pain in salivary glands
  6. Bronchitis

Secreted in breast milk

  • Goiter in infants
  • Inhibit thyroid hormone production
  • Hinder development, especially the brain

AVOID breast-feeding

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

MoA of carbimazole

A

In vivo conversion to methimazole

Inhibit thyroid peroxidase,
hence inhibit organification (iodination of tyrosine residue in thyroglobulin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

MoA of methimazole

A

Inhibit thyroid peroxidase,

hence inhibit organification (iodination of tyrosine residue in thyroglobulin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

MoA of propylthiouracil

A

Inhibit thyroid peroxidase,
hence inhibit organification (iodination of tyrosine residue in thyroglobulin)

Inhibit T4 conversion to T3 in peripheral tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Side effects of thionamides

A
  1. Skin rash and pruritus: may add anti-histamine
  2. Bone marrow depression: thrombocytopenia, agranulocytosis
  3. Cross placenta, secreted in breast milk: Lowest effective dose + close monitoring

(Liver failure)
(High recurrence rate)

17
Q

Use of thionamides

A

Long-term treatment for hyperthyroidism

  • Slow onset (3-4 weeks to deplete thyroid hormone store)
  • Usually given 12-18 months
  • Higher dose in the beginning
  • Become euthyroid –> reduce dose
  • Propylthiouracil: can be used for patients allergic to carbimazole
18
Q

Use of radioiodine

A

Long-term treatment for hyperthyroidism

  • For relapse after thionamide therapy
  • To ablate residual thyroid tumor tissue after surgery
  • Single dose is used (recurrence rare given adequate dose)
  • Cytotoxic effect on the gland is delayed for 1-2 months.
19
Q

MoA of I-131

A
  • Radioactive iodine taken up by follicular cells
  • Emit beta radiation, damage thyroid gland
  • ↓thyroid cells
  • ↓thyroid hormone production
20
Q

Side effects of I-131

A
  1. Hypothyroidism (irreversible)
    - Thyroxine replacement therapy
  2. Potential damage to the thyroid gland of fetus and infants
    - Avoided in breast-feeding / pregnant women

*NO solid evidence of inducing cancer / infertility

Pharmacology (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions