L34- Thyroid and Antithyroid Drugs (hyperthyroid) Flashcards Preview

DERS (endo/repro pharm) > L34- Thyroid and Antithyroid Drugs (hyperthyroid) > Flashcards

Flashcards in L34- Thyroid and Antithyroid Drugs (hyperthyroid) Deck (17)
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1

describe the management hierarchy for hyperthyroidism

1) pharmacotherapy
2) radioactive iodine (RAI) destruction of thyroid
3) surgical thyroidectomy

2

list the pharmacological agents for hyperthyroidism

-thioamides
-iodides
-β-blockers
-glucocorticoids
-bile acid sequestrants

3

Thioamides:
-(1) agents
-(2) MOA

1- methimazole, PTU (propylthiouracil)

2- inhibits thyroid peroxidase enzyme --> prevents iodide oxidation to iodine (+ --> interferes with iodination of tyrosyl groups on thyroglobulin --> inhibits coupling of iodotyrosyl residues --> inhibits TH formation)

4

Thioamide:
-(1) is preferred agent because of (2) and except for in (3) situations
-(3) drug has (4) as additional MOA

1- methimazole > propylthiouracil (PTU)

2- less toxic (liver injury), longer 1/2 life and duration (once daily)

3- (PTU) severe hyperthyroid, thyroid storms, 1st trimester

4- inhibits peripheral deiodination (T4 --> T3)

5

list the therapeutic uses of Thioamides

-definitive Tx for hyperthyroidism

-conjunction w/ radioative iodine (quickens recovery)

-control hyperthyroid in preparation for surgery

6

describe the role and regimen of iodides for hyperthyroidism

Iodides inhibit hormone release via thyroglobulin proteolysis inhibition and transient iodine organification inhibition

-NOT used alone b/c thyroid escapes iodide block in 2-8wks

7

list the clinical applications of iodides

-Thyroid Storm: rapid improvement of Sxs

-preop for surgery --> dec thyroid size, vascularity of hyperplastic thyroids

-radiation emergencies involving release of radioactive iodine isotropes

8

iodides AEs

(uncommon)
-precipitates hyperthyroidism (Jod-Basedow phenomenon) or hypothyroidism (no escape from Wolff-Chaikoff)

-delays onset of thioamide therapy -- prevents use of radioactive iodine therapy for several weeks

-fetal goiter if used in pregnancy

9

describe the use of β-blockers in hyperthyroidism

-alleviate the SNS / catecholamine Sxs precipitated by TH inc sensitivity to SNS

-Propanolol inhibits T4 --> T3

-CCBs to control tachycardia if β-blockers are contraindicated

10

describe the use of glucocorticoids in hyperthyroidism

-inhibits peripheral T4 --> T3
-promotes vasomotor stability
-treats possible associated adrenal insufficiency Sxs

Manages Grave's ophthalmopathy and dermopathy

11

describe the use of bile acid sequestrants in hyperthyroidism

binds to TH metabolites to inhibit enterohepatic cycling of TH

12

_____ is generally the preferred hyperthyroidism Tx

RAI- radioactive iodine (I-131)
-destroy thyroid parenchyma

13

list RAI AEs

-hypothyroidism
-radiation thyroiditis
-exacerbates Grave's ophthalmopathy

-destroys fetal thyroid in pregnancy

14

Thyroid storms are triggered by....

infection
trauma
surgery
physical illness
severe emotional distress

15

thyroid storm management

-supportive therapy
-treat underlying disease process / trigger

-PTU (propylthiouracil), iodides, propanolol, corticosteroids, bile acid seqesterants

16

Amiodarone induced thyrotoxicosis 1:
-(1) definition
-(2) lab features
-(3) Tx

1- inc TH synthesis

2- low TSH, elevated T3/T4

3- antithyroid drugs

17

Amiodarone induced thyrotoxicosis 2:
-(1) definition
-(2) lab features
-(3) Tx

1- destructive thyroiditis

2- low TSH, elevated T3/T4

3- glucocorticoids