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PCM Exam 2 Pharm > ADRENERGIC AGONISTS & ANTAGONISTS 1 > Flashcards

ADRENERGIC AGONISTS & ANTAGONISTS 1 Flashcards

1
Q

What disorders will you use Adrenergic agonists and antagonists ?

A
  • Hypertension
  • Angina
  • Heart failure
  • Arrhythmias
  • Asthma
  • Migraine
  • Anaphylactic reactions
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2
Q

What receptors are exclusive for the skin and what effect does norepinephrine and epinephrine have?

A

a1 receptors and it causes vasoconstriction

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3
Q

What receptors are located smooth muscle of blood vessels? What are their effects?

A
  • B2 and a1
  • Activation of B2 receptors causes vasodilation.
  • Activation of a1 receptors causes vasoconstriction.
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4
Q

What effect does low dose of Epinephrine causes on the smooth muscle of blood vessels

A
  • B2 receptors are more sensitive to epinephrine than a1 receptors
  • low concentrations of epinephrine cause vasodilation.
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5
Q

What does high doses of Epinephrine do on the smooth muscle of blood vessels?

A

at high concentrations of epinephrine, both
a1 and B2 receptors are activated, and the response to a1 receptors predominates, therefore vasoconstriction results.

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6
Q

What are the endogenous direct acting ADRENERGIC AGONISTS?

A

• EPINEPHRINE • NOREPINEPHRINE • DOPAMINE

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7
Q

What occurs at low and high concentrations of EPINEPHRINE

A
  • At low concentrations epinephrine activates mainly b1 and b2 receptors.
  • At higher concentrations a1 effects become more pronounced.
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8
Q

What are the major 9 effects of EPINEPHRINE and what receptor is activated?

A

EPINEPHRINE: EFFECTS

  • Increases heart rate and contractile force ( b1 effect).
  • Cardiac output increases: oxygen demand of the myocardium increases.
  • Increases renin release (b1 effect).
  • Constricts arterioles in skin and viscera (a1 effect).
  • Dilates blood vessels of skeletal muscle (b2 effect).
  • Relaxes bronchial smooth muscle (b2 effect).
  • Increases liver glycogenolysis (b2 effect).
  • Increases glucagon release (b2 effect).
  • Increases lipolysis (b1 and b2 effect).
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9
Q

What occurs at a large IV dose of epinephrine?

A

When a large dose is given IV

• There is increase in blood pressure. Due to:

  1. Increased ventricular contraction ( b1 effect).
  2. Increased heart rate (b1 effect) This may be opposed by the baroreceptor reflex.
  3. Vasoconstriction (a1 effect).
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10
Q

What occurs at a low IV dose of EPINEPHRINE

A
  • Peripheral resistance decreases, because b2 receptors are more sensitive to epinephrine than a1 receptors. Diastolic pressure falls.
  • Systolic pressure increases due to increased cardiac contractile force (b1 effect).
  • Heart rate increases (b1 effect).
  • There is no increase in mean blood pressure, so the baroreceptor reflex does not kick in.
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11
Q

What are the main uses of EPINEPHRINE

A
  • Anaphylactic Shock: drug of choice.
  • Acute asthmatic attacks.
  • Cardiac arrest
  • In Local Anesthetics: Epinephrine increases duration of local anesthesia by producing vasoconstriction at the site of injection.
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12
Q

What are the effects of NOREPINEPHRINE and what receptors are impacted?

A
  • Causes peripheral vasoconstriction ( a1 effect).
  • Increases cardiac contractility (β1 effect).
  • Increases peripheral vascular resistance, systolic blood pressure and diastolic blood pressure.
  • Cardiac output is unchanged or decreased.
  • The increase in blood pressure triggers a baroreceptor reflex resulting in bradycardia.
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13
Q

What are the main uses of NOREPINEPHRINE

A

• To treat shock because it increases vascular resistance and therefore increases blood pressure.

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14
Q

What is the baroreceptor effect when there is vasocontriction in the blood vessel that causes an increase in blood pressure?

A

the increase in blood pressure is sensed by the carotid sinus activating the parasympathetics in the vagal centers and inhibting the sympathetics

ultimatly causing a decrease in heart rate and decrease in force of contraction

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15
Q

What is the baroreceptor effect when there is vasodilation in the blood vessel that causes an decrease in blood pressure?

A

the decrease in blood pressure is sensed in the carotid sinus inhibiting the parasympathetics and simulatinf the sympathetic activity in the sympathetic centeres

ultimatly causing an increase in heart rate and force of contraction

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16
Q

what happens when atropine is given before norepinephrine?

A

norepinephrine causes tachycardia because of the uninhibited B1 effect causing an increase in heart rate

17
Q

what occurs at low rates of infusion of dopamine?

A

• Dopamine activates D1 receptors, in renal and
other vascular beds, leading to:
• Vasodilation

  • Increase in GFR
  • Increase in renal blood flow
  • Increase in sodium excretion
18
Q

what occurs at Intermediate rates of infusion of dopamine?

A

Intermediate rates of infusion

  • Dopamine activates β1 receptors in the heart, increasing cardiac output.
  • There is negligible activation of β2 receptors.
  • Dopamine causes release of NE from nerve terminals, which contributes to its cardiac effects.

causes:

Dopamine increases SBP. • DBP is usually not changed significantly. • MAP is increased. • PVR is unchanged.

19
Q

What occurs at high rates of dopamine?

A

High rates of infusion

  • Dopamine activates vascular a1 receptors, leading to vasoconstriction and a rise in blood pressure.
  • Total peripheral resistance may be increased.

uses:

• Used in the treatment of severe CHF. • Used in the treatment of cardiogenic and septic shock. • For management of shock intermediate to high rates of infusion are used.

20
Q

What is the NON-SELECTIVE B-ADRENERGIC AGONISTS and its effect

A

ISOPROTERENOL
• Activates b1 and b2 adrenergic receptors.

  • Increases heart rate, force of contraction, and cardiac output ( b1 effect).
  • Dilates arterioles of skeletal muscle (b2 effect), resulting in a decrease in peripheral vascular resistance.
  • Diastolic pressure falls. Systolic blood pressure may remain unchanged or rise.
  • Mean arterial pressure typically falls.
  • Causes bronchodilation (b2 effect).
  • Isoproterenol may be used in emergencies to stimulate heart rate in patients with bradycardia or heart block.
21
Q

What is the b1-SELECTIVE ADRENERGIC AGONISTS

A

B 1-SELECTIVE ADRENERGIC AGONISTS

DOBUTAMINE

  • Predominantly a b1 agonist.
  • Potent inotrope, with comparatively mild chronotropic effects.
  • Produces less increase in HR and less decrease in PVR than isoproterenol.
  • Causes mild vasodilation.
  • Increases myocardial O2 consumption. This is the basis of the dobutamine stress echocardiogram.
22
Q

What is the effect of the b 1-SELECTIVE ADRENERGIC AGONISTS

A

DOBUTAMINE

  • Management of acute heart failure.
  • Management of cardiogenic shock.
23
Q

What are the b 2-ADRENERGIC AGONISTS and their effects and its adverse effects?

A
  • Evoke bronchodilation (b2 effect)
  • Used in asthma.

SHORT-ACTING • Albuterol • For management of acute asthma symptoms.

LONG-ACTING • Salmeterol & formoterol • Prolonged duration of action: 12 hours. • Slow onset of action: not for prompt relief of acute
symptoms.

• adverse effects: Tremor, restlessness, apprehension, anxiety,
tachycardia.

24
Q

What is the  1-SELECTIVE ADRENERGIC AGONISTS and what is it used for?

A

PHENYLEPHRINE

• Vasoconstriction: a1 effect.

Baroreceptor reflex: bradykardia

• Nasal decongestant .

Given orally or topically.

• Mydriatic.

• Used to increase blood pressure in hypotension resulting from
vasodilation in septic shock or anesthesia.

• Used to increase blood pressure and terminate episodes of supraventricular tachycardia.

25
Q

CLONIDINE falls under what category and whats its effects?

A

a 2-SELECTIVE ADRENERGIC AGONISTS

  • Partial a2 agonist.
  • Centrally acting antihypertensive.
  • Activates central presynaptic a2-adrenoceptors.
  • Reduces sympathetic outflow. This reduces blood pressure.
  • Adverse effects: lethargy, sedation, xerostomia.
26
Q

METHYLDOPA falls under what category and whats its effect?

A

a2-SELECTIVE ADRENERGIC AGONISTS

  • Taken up by noradrenergic neurons.
  • Converted to a-methylnorepinephrine which activates central a2-adrenoceptors.
  • This decreases blood pressure.

• Drug of choice for treatment of hypertension
during pregnancy.

• Adverse effects: sedation, impaired mental
concentration, xerostomia.

27
Q

BRIMONIDINE falls under what category and whats its effect?

A

a2-SELECTIVE ADRENERGIC AGONISTS

  • Highly selective a2 agonist.
  • Given ocularly to lower intraocular pressure in glaucoma.
  • Reduces aqueous humor production and increases outflow.
28
Q

AMPHETAMINE falls under what category and whats its effect

A

RELEASING AGENTS for norepinephrine

  • Has central stimulatory action.
  • Can increase blood pressure by a-agonist action on vasculature as well as b-stimulatory effects on heart.

USES • ADHD • Narcolepsy

29
Q

METHYLPHENIDATE falls under what category and whats its effect?

A

RELEASING AGENTS for norepinephrine

  • Structural analogue of amphetamine.
  • Used to treat ADHD in children.
30
Q

TYRAMINE falls under what category and whats its effect?

A

RELEASING AGENTS for norepinephrine

  • Found in fermented foods such as ripe cheese and Chianti wine.
  • Normally oxidized by MAO.
  • If the patient is taking MAO inhibitors, it can precipitate serious vasopressor episodes.
31
Q

COCAINE falls under what category and whats its effect

A

UPTAKE INHIBITORS

  • Blocks monoamine reuptake.
  • Monoamines accumulate in synaptic space.
  • This results in potentiation and prolongation of their central and peripheral actions.
32
Q

ATOMOXETINE falls under what category and whats its effect?

A

UPTAKE INHIBITORS

  • Selective inhibitor of the norepinephrine reuptake transporter.
  • Indicated for the treatment of ADHD.
33
Q

MODAFINIL falls under what category and whats its effect?

A

UPTAKE INHIBITORS

  • Psychostimulant.
  • MOA not fully known.
  • Inhibits norepinephrine and dopamine transporters.
  • Increases synaptic concentrations of norepinephrine, dopamine, serotonin and glutamate, and decreases GABA levels.
  • Used for the treatment of narcolepsy
34
Q

EPHEDRINE effects?

A

Induce release of norepinephrine

Not a catecholamine: poor substrate for COMT and MAO. Long duration of action.

  • Excellent absorption orally and penetrates the CNS.
  • Used as a pressor agent, particularly during spinal anesthesia.
  • Used in myasthenia gravis.
35
Q

PSEUDOEPHEDRINE effects?

A
  • Induce release of norepinephrine
  • Activate adrenergic receptors.
  • One of four ephedrine enantiomers.
  • Available over the counter as a component of many decongestant mixtures.

PCM Exam 2 Pharm (14 decks)

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