Adrenoceptor Agonist Flashcards

Exam 4

1
Q

Adrenoceptor agonist

A
  • useful in many clinical conditions
  • drugs affinity will determine their effect
  • classified as either alpha or beta
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2
Q

Alpha 1 receptors

A
  • postynaptic smooth muscle, exocrine glands, and CNS
  • contraction of vascular smooth muscle (increase BP), iris dilator muscle (mydriasis), smooth muscle in lower urinary tract (bladder, urethra, and prostate)
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3
Q

Alpha 2 receptors

A
  • presynaptic nerve endings
  • causes feedback inhibition to prevent further release of NE
  • also found on platelets, intestinal, hepatic,, renal, endocrine tissue, ocular, adipose
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4
Q

Beta 1 receptors

A
  • produce cardiac stimulation
  • increase HR
  • increase contractility
  • increase cardiac impulse conduction
  • increase renin secretion
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5
Q

Beta 2 receptors

A
  • mediate relaxation of bronchial, uterine, and vascular smooth muscle
  • skeletal muscle (increase glucose in blood)
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6
Q

Beta 3 receptors

A

-promote lipolysis

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7
Q

Dopamine receptor

A
  • activated by dopamine only
  • D1 receptors mediate vascular smooth muscle relaxation
  • D2 receptors modulating neurotransmitter release
  • Fenoldopam is D1 receptor agonist
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8
Q

Imidazoline receptor

A
  • activated by adrenoceptor agonist and substances containing imidazoline structures
  • found in CNS
  • Clonidine: activates both alpha 2 and imidazoline to decrease BP
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9
Q

Classification of adrenoceptor agonist

A
  • direct acting agonist
  • indirect acting agonist
  • mixed acting agonist
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10
Q

Direct acting agonist

A
  • bind to and activate adrenoceptors
  • cateholamines: epi, NE, dopamine, isoproterenol, dobutamine
  • noncatecholamines: albuterol, clonidine, midodrine, oxymetazoline, phenylephrine, terbutaline
  • catecholamines are broke down quickly
  • noncatecholamines have longer DOA
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11
Q

Epinephrine

A
  • adrenergic agonist
  • low dose: beta effects on vascular system
  • high dose: alpha effects are strongest
  • clinical uses: bronchospasm, glaucoma, anaphylactic shock, in anethestics
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12
Q

Norepinephrine

A
  • adrenergic receptors
  • alpha adrenergic is most effected more than beta
  • vasoconstriction and increase BP
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13
Q

Isoproterenol

A
  • strong beta 1 and 2 receptor agonist with little alpha effect
  • increases HR
  • no blood vessel constriction so no increased BP
  • clinical use: stimulate heart
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14
Q

Dopamine

A
  • activates alpha and beta adrenergic receptors
  • therapeutic dose: stimulates beta 1 of heart
  • high dose: activates alpha receptors and cause vasoconstriction
  • also activates dopaminergic receptors in renal vasculature (increases blood flow to kidneys)
  • clinical uses: shock and CHF
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15
Q

Dobutamine

A
  • beta 1 receptor agonist
  • increase contractility and HR
  • more beta 2 than alpha 1: mild vasodilation
  • clinical uses: acute heart failure
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16
Q

Albuterol

A
  • Beta 2 agonist

- relieves bronchoconstriction

17
Q

Terbutaline

A
  • beta 2 agonist
  • used in asthma for bronchodilation effect
  • used in pregnancy to relax uterus and prevent pre-term labor
18
Q

Fenoldopam

A
  • D1 agonist

- used for hypertensive crisis: vasodilator of coronary and peripheral arteries

19
Q

Phenylephrine

A
  • alpha agonist (more 1 than 2)

- used in hypotension and rhinitis

20
Q

Adrenergic agonist effect on blood vessels

A
  • alpha 1: increase vascular smooth muscle contraction, increases arterial resistance, and increase BP
  • Beta 2: vasodilation leading to decrease in BP, bronchodilation in lungs
21
Q

Adrenergic agonist effect on heart

A
  • beta 1
  • increase HR (+ chronotropy)
  • increase force of contraction (+ inotropy)
22
Q

Adrenergic agonist effects of eye

A
  • alpha 1: increase pupillary dilator muscle contraction (mydriasis)
  • alpha 2: decrease aqueous humor production
23
Q

Adrenergic agonist effects on respiratory tract

A
  • beta 2 receptors
  • located in bronchial airway
  • stimulation relaxes bronchial smooth muscle
  • opens the airway
  • clinical use: asthma (ex. albuterol)
24
Q

Adrenergic agonist effects of GU tract

A
  • beta 2: decrease uterine tone (relaxes)

- alpha 1 and 2: increase bladder sphincter contraction

25
Q

Adrenergic agonist effects on CNS

A
  • alpha 2 receptors
  • elevate mood, make more alert, and suppress appetite
  • clinical use: narcolepsy, ADD, weight control
  • only adrenergic agonist that get into CNS have these effects
26
Q

Adrenergic agonist effects on total body

A
  • stimulation of all adrenergic receptors (alpha 1/2, beta 1/2)
  • anaphylaxis: bronchospam, low BP
  • example: epi
27
Q

ADR

A
  • cerebral vascular system effects are most important/life threatening toxicity
  • excessive doses of catecholamines reduce blood flow to vital organs or cause excessive cardiac stimulation
  • lead to HTN, cardiac arrhythmias, cardiac ischemia leading to MI and heart failure
  • primarily occur if heart is already sick
28
Q

Amphetamine

A
  • indirect acting adrenergic agonist
  • can prevent NE from being taken back up into presynaptic neuron which leaves more NE in synpatic cleft to bind to adrenergic receptors
  • can also enter presynaptic terminal and displace stored NE for release into synpatic cleft
29
Q

Tyramine

A
  • found in fermented foods

- also enters presynaptic terminal and displace stored NE for release into synaptic cleft

30
Q

Ephedrine

A
  • release NE from neuron
  • directly stimulates alpha and beta receptors
  • clinically use pseduoephedrine as nasal decongestant