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MOD II > TBL 11 - Adrenergic Agonists and Antagonists > Flashcards

TBL 11 - Adrenergic Agonists and Antagonists Flashcards

1
Q

Describe the synthesis mechanism of dopamine.

A

Tyrosine is transported into the neurons by Na+-Tyrosine cotransporter and catalyzed by tyrosine hydroxylase to dihydroxyphanylalanin (L-DOPA), which is then converted to dopamine.

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2
Q

What drug inhibits tyrosine hydroxylase?

A

Methyltyrosine

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3
Q

What transports dopamine into vesicles?

A

Vesicular Monoamine Transported (VMAT)

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4
Q

What inhibits VMAT?

A

Reserpine

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5
Q

What enzyme converts dopamine to NE?

A

Intravesicular B-hydroxylase

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6
Q

What 2 drugs inhibit the release of NE from vesicular membranes depolarized by Ca2+ influx?

A

Bretylium and Guanethidine

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7
Q

What two types of drugs inhibit the re-uptake transporter of NE?

A
  • TCA (tricyclic antidepressants)
  • Cocaine
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8
Q

What two enzymes degrade NE in the synaptic cleft?

A
  • Catechol-O-methyltransferase (COMT)
  • Monoamine oxidase (MO)
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9
Q

Describe Adrenergic receptors.

A

All have 7 ransmembrane domains and are coupled to G-proteins.

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10
Q

Where are alpha-1 receptors located and how do they act?

A
  • Arterioles: constriction and increased BP
  • Radial Muscle: constriction and mydriasis
  • Kidney: decreased renin release
  • Bladder: increased contraction and sphincter tone
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11
Q

Where are alpha-2 receptors located and how do they act?

A
  • Presynaptic: decrease NE release
  • Pancreas: decrease insulin release
  • Platelets: increase aggregation
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12
Q

Where are Beta-1 receptors located and how do they act?

A
  • Heart: increase HR and contraction
  • Kidney: increase renin release
  • Eye: increase aqueous humor
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13
Q

Where are Beta-2 receptors located and how do they act?

A
  • Vessels: vasodilation and decreased diastolic pressure
  • Uterus: relaxation and decreased muscle tone
  • Bronchioles: relaxation and bronchodilation
  • Metabolic: increased gluconeogenesis in the liver
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14
Q

Where are dopamine receptors located and how do they act?

A

They are located on the renal, mesenteric, and coronary vessels and cause vasodilation.

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15
Q

What G protein subtype is acted on by alpha-1, alpha-2, beta-1, and beta-2 receptors?

A

Gq - Alpha-1
Gi - Alpha-2
Gs - Beta-1 and Beta-2

(QISS)

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16
Q

What type of receptors does Epinephrine work on and what is it used for?

A

Epinephrine is an agonist of all adrenergic receptors and if the first choice of medicine to treat anaphylaxis caused by peanut allergies and bee stings.

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17
Q

What are the effects of Epinephrine on the alpha-1 receptor?

A
  • Increases peripheral vascular resistance
  • Decreases edema
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18
Q

What are the effects of Epinephrine on the beta-1 receptor?

A
  • Increases contractility and heart rate.
19
Q

What are the effects of Epinephrine on the beta-2 receptor?

A
  • Bronchodilation
  • Decreases the release of mediators from mast cells and basophils
20
Q

At low concentrations, what receptors does Epinephrine affect?

A

B1 and B2 receptors

21
Q

At high concentrations, what receptors does Epinephrine affect?

A

a1

22
Q

What is the first line agent for septic shock?

A

NE

23
Q

What type of drugs does sepsis with fluid-unresponsive hypotension need to maintain BP?

A

Vasopressors

24
Q

What receptors does NE work on?

A
  • Agonist at a1 > B1 where it is a potent vasoconstrictor.
  • Has minimal effects as B2.
25
Q

What are the clinical uses for Phenylephrine?

A
  • Hypotension
  • Shock
  • Maintains BP during surgery
  • Nasal and ocular decongestion
  • Mydriasis without cycloplegia
26
Q

What type of receptors does Phenylephrine activate?

A

Agonist at a1.

27
Q

What are some adverse effects of Phenylephrine?

A
  • Rebound nasal congestion on prolonged use > 3 days
  • Hypertension
28
Q

What is the most often cause of cardiogenic shock?

A

Acute myocardial infarction with left ventricular failure.

Hypoperfusion caused by low CO despite adequate IV volume.

29
Q

At low doses, what receptors does Dopamine predominantly act on and what do they cause?

A
  • D1 receptors
  • Cause vasodilation in the renal, mesenteric, and coronal vasculature.
30
Q

At intermediate doses, what receptors does Dopamine predominantly act on and what do they cause?

A
  • B1 receptors
  • Acts as an inotrope.
31
Q

At high doses, what receptors does Dopamine predominantly act on and what do they cause?

A
  • a1 receptors
  • Vasoconstriction
32
Q

What type of drug is Dobutamine?

A
  • B1 agonist and cardiac stimulant
33
Q

What is the MOA of Dobutamine?

A
  • Selectively increases myocardial contractility
  • Decreases vascular resistance by activating B2 adrenoceptors
  • Decreases the impedance to ventricular ejection
34
Q

How does Dobutamine work in those with hypoperfusion?

A

Contributes to an increase in stroke volume and CO.

35
Q

What receptor does a-Methyldopa act on, what type of drug is it, and what is its MOA?

A
  • Alpha-2
  • Sympathomimetics (alpha-2 agonist)
  • It is a prodrug that is converted to its active metabolite methyl-NE in the brain and it is used to treat HTN in pregnancy.
36
Q

What are some adverse effects of a-Methyldopa?

A
  • Immunologic effects
  • Coombs positive hemolytic anemia
  • Autoimmune hepatitis
37
Q

What receptor does Clonidine act on, what type of drug is it, and what is its MOA?

A
  • Alpha-2
  • Sympathomimetic (alpha-2 agonist)
  • Activates a2 receptors in the medulla (brain stem) that works with the NE feedback loop and decreases NE release in order to treat hypertensive urgencies, ADHD, and Tourette Syndrome (multiple motor ticks and 1 or more vocal ticks).

Rarely used as a long-term hypertensive drug.

38
Q

What are some adverse effects of Clonidine?

A
  • Rebound hypertension
  • Abrupt cessation of drug causes severe hypertension and symptoms of high BP and sympathetic over-activity (nervousness, sedation, sweating, headache, and chest pain).
39
Q

What receptor does Apraclonidine act on, what type of drug is it, and what is its MOA?

A
  • Alpha-2
  • Sympathomimetic (alpha-2)
  • Decreases BP by reducing CO, HR, and vascular resistance via relaxation of blood vessels in order to treat Glaucoma by decreasing intra-ocular pressure.
40
Q

What adverse effect does Apraclonidine have?

A

Sudden withdrawal causes rebound HT.

41
Q

What receptor does Fenoldopam act on, what type of drug is it, and what is its MOA?

A
  • D1 receptors
  • Sympathomimetic (D1 agonist)
  • Dilates the peripheral arterioles to decrease BP in hypertensive emergencies.
42
Q

What are some adverse effects of Fenoldopam?

A
  • Hypotension
  • Tachycardia
  • Flushing
  • Headache
  • Nausea
43
Q

What receptor does Phenylephrine act on, what type of drug is it, and what is its MOA?

A
  • Alpha-1
  • Sympathomimetic (alpha-1 agonist)
  • Causes vasoconstriction and dilator contraction to constrict nasal mucous membranes and mydriasis (dilation of pupil), which reduces blood flow.
44
Q

What are the clinical uses of Phenylephrine?

A
  • ## Used topically or orally as a nasal decongestant caused by viral/allergic rhinitis.

MOD II (8 decks)

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