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Pharmacology Exam V > Thyroid/Anti-thyroid drugs > Flashcards

Thyroid/Anti-thyroid drugs Flashcards

1
Q

Thyroid hormone functions

A

growth
development
body temp
energy/metabolism

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2
Q

Thyroid hormone synthesis steps (4)

Takes place what two places?

A

iodide uptake into thyroid gland (Na/I symporter)

peroxidase mediated oxidation to iodine

iodination of tyrosine residues inside THYROGLOBULIN molecule - formation of MIT and DIT

combine MIT and DIT

follicular cells and follicular colloid

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3
Q

Secretion of thyroid hormone

T4:T3?

how much of each is free?

A

thyroglobulin taken up by thyroidc ell

degradation releases thyroid hormones

ratio of T4 to T3 - approximately 5:1

.04 of T4 and .4 of T3

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4
Q

Thyroid hormones bind where?

A

Intranuclear

binds T3 receptor in nucleus

T4 has to be converted to T3 by deiodinase enzyme - then binds T3 Receptor

T3R heterodimerizes with RXR to INCREASE GENE TRANSCRIPTIONS

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5
Q

Hypothalamus releases _______ that acts on the anterior pituitary to release ______

Promotes synthesis of what?

Product then does what?

A

TRH
TSH

T3 and T4

negative feedback - decrease hypothalamus and ant pituitary synthesis

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6
Q

How does iodide affect synthesis?

A

high inhibits –> SHORT TERM, can be overcome

low promotes

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7
Q

Thyroid hormone effects on sympathetic nervous system

A

increase Beta receptors

Decrease alpha

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8
Q

Thyroid hormone effects on growth/development

A

brain development and neurogenesis

bone growth and skeletal maturation

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9
Q

Thyroid hormone effects on thermogenic

A

increase cell energy consumption - heat production

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10
Q

Thyroid hormone effects on respiratory

A

increase O2 consumption in most tissues - increase CO2 production - increase respiratory rate

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11
Q

Thyroid hormone effects on CNS

A

rapidity of cerebration (thinking)

muscle tone increase

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12
Q

Thyroid hormone effects on GI

A

increase secretions and motility

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13
Q

Thyroid hormone effects on skin and hair

A

growth promoting in skin, nail, hair

prevent accumulation of glycosaminoglycans in interstitial space

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14
Q

Thyroid hormone effects on CV

A

increase heart rate, contractility, CO, blood volume

decrease vascular resistance

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15
Q

Thyroid hormone effects on metabolism

A

decrease circulating cholesterol

increase intestinal carb absorption, glycolysis, gluconeogenesis, insulin production

increase protein synth and catabolism

increase need and usage of vitamins

overal INCREASE IN METABOLIC RATE

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16
Q

Type I (Primary Hypothyroidism) Causes

A

Congenital Defect

Autoimmune thyroiditis (Hashimoto’s)

Iodide Deficiency

Others - radiation, surgical removal, medications

17
Q

Secondary Hypothyroidism

A 
head trauma
cranial neoplasm
brain infection
cranial irradiation
neurosurgery
18
Q

Drugs for hypothyroidism (3)

treatment of choice

treatment goals (2)

Special consideration of treatment

A

levothyroxine (T4)
liothyroxine (T3)
liotrix (T3/T4)

levothyroxine

increase T4 blood concentrations, normalize TSH levels

coronary artery disease in the elderly, may be protective

19
Q

Causes of primary hyperthyroidism

A 
Grave's
Thyroid adenoma/carcinoma
Autoimmune Thyroiditis (Hashimoto's)
Thyroid storm
Excess iodide
20
Q

Secondary Hyperthyroidism

A

Dysfunction of hypothalamus or pituitary - autosecretio of TSH or TRH

21
Q

thioamides (2)

MOA

A

methimazole
propylthiouracil

INHIBIT PEROXIDASE REACTION, IODINE ORGANIFICATION, AND COUPLING OF IODOTYROSINES

22
Q

Methimazole, Propylthiouracil (PTU) Adverse effects

Pharmacologic considerations (3)

A

rash, nausea, GI, agranulocytosis

Methimazole - altered taste/smell

PTU - fatal hepatitis

PROTEIN BINDING

both CROSS PLACENTA - PTU is safer in pregnancy

PTU in thyroid storm

23
Q

Iodide antithyroid agents (2)

MOA

A

potassium iodide
lugol’s solution

inhibits PROTEOLYSIS OF TgB

24
Q

Potassium Iodide, Lugol’s Solution

Key considerations (3)

A

ONLY INHIBIT FOR 2 TO 8 WEEKS

withdrawal can induce THYROTOXICOSIS

rapid onset - USEFUL FOR THYROID STORM

surgical benefit - decrease size of hyperplastic gland

25
Q

Radioactive iodine MOA

main adverse effect

A

gamma and beta rays

beta rays - destroy parenchymal cells

hypothyroidism - due to destruction of cells

26
Q

Anion inhibitors (3)

MOA

A

perchlorate
pertechnetate
thiocyanate

INHIBIT UPTAKE OF IODIDE by inhibiting Na/I transporter

27
Q

Anti-thyroid Key adjuncts (4)

A

Propanolol - beta blocker

Diltiazem - calcium channel blocker - control tachycardia

Barbiturates - increase T4 metabolism

Bile acid sequestrants - cholestyramine

28
Q

Propanolol MOA

A

beta-1/beta-2 antagonist

also inhibits CONVERSION OF T4 TO T3

asthma, AV blockade, hypotension, bradycardia

Pharmacology Exam V (11 decks)

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