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Pharmacology- Test 2 > Adrenergic Drugs > Flashcards

Adrenergic Drugs Flashcards

1
Q

What is the biosynthesis and release of Catecholamines pathway? (8)

A

(1) Phenylalanine to Tyrosine (enzyme: phenylalanine hydroxylase)
(2) Tyrosine uptake into nerve cell
(3) Tyrosine to DOPA (enzyme: tyrosine hydroxylase)
(4) Dopa to Dopamine (enzyme: aromatic acid decarboxylase)
(5) Uptake of Dopamine into storage granules by active transport mechanism (also transports NE)
(6) Dopamine to NE (enzyme: dopamine beta-hydroxylase)
(7) NE to Epinephrine in adrenal medulla (enzyme: phenylethanolamine N- methyl transferase)
(8) Release of NE into synaptic cleft during nerve stimulation. Storage vesicles, containing the NE, fuse with neuronal membrane

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2
Q

What is the rate limiting step of the biosynthesis of Catecholamines?

A

Tyrosine Hydroxylase

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3
Q

What are 3 Catecholamines? Which one is the most prevalent?

A

(1) Norepinephrine**
(2) Epinephrine
(3) Dopamine

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4
Q

What are the 3 ways in which catecholamines are removed from biophase?

A

(1) Neuronal reuptake (uptake 1). Active transport of catecholamine into neuron where metabolized or taken back up into storage granule
(2) Diffusion into circulation
(3) Active transport (uptake 2) into post-junctional cells

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5
Q

What is the most important process in the removal of catecholamines?

A

Uptake 1 (pre-synaptic uptake mechanism)

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6
Q

What are the 2 ways the catecholamines are metabolized?

A

(1) Monoamine Oxidase (MAO): located in both neurons and post-junctional cells. Deaminates catecholamines
(2) Catechol-O-methyltransferase (COMT): located in post-junctional cells. Catalyzes the O-methylation of catecholamines

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7
Q

What are the two systems that impact the Sympathetic Nervous System? What do they do?

A
  • Sympathomimetics: mimics SNS activation and enhances SNS activity
  • Sympatholytics: block sympathetic neurotransmission
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8
Q

What are the 3 types of Sympathomimetics?

A

(1) Direct activity: act directly on the receptor (Epi, NE, Isoproterenol)
(2) Indirect activity: effect catecholamine levels in synapse (e.g. catecholamine release or uptake- Amphetamine, Tyramine, Cocaine, Imipramine)
(3) Combination: have mixed actions (Dopamine, Ephedrine)

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9
Q

What does indirect activity of sympathomimetics mean?

A

The actions of an indirect agent are dependent upon the presence of endogenous catecholamines (bind to post-synaptic adrenergic receptors)

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10
Q

What are the 3 Catecholamine Receptors?

A

(1) Alpha-adrenergic receptors
(2) Beta-adrenergic receptors
(3) Dopamine receptors

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11
Q

What are the subtypes of Alpha receptors? What are they known for doing?

A

(1) Alpha-1: smooth muscle contraction (vasoconstriction)

2) Alpha-2: pre-synaptic regulation of NT release (negative feedback mechanism

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12
Q

What are the non-selective Alpha agonists and antagonists?

A
  • Agonists: Epi>NE>Isoproterenol (Epi and NE are better than Isoproterenol which is a beta agonist)
  • Antagonists: Phentolamine and Phenoxybenzamine
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13
Q

What are the subtypes of Beta receptors? What are they known for doing?

A

(1) Beta-1: cardiac stimulation (heart rate, contractility)

2) Beta-2: smooth muscle: bronchodilation (lung) and vasodilation (e.g. vessels in skeletal muscle

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14
Q

What are the selective Alpha receptor subtypes?

A

Alpha-1: selective agonist- Phenylephrine
selective antagonist: Prazosin
Alpha-2: selective agonist: Clonidine
selective antagonist: Yohimbine

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15
Q

What is the non-selective Beta antagonist?

A

Propranolol

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16
Q

What are the Agonists and Antagonists of Beta receptors?

A

Beta-1: Agonists potency rank Iso>Epi=NE
- selective antagonist: Metoprolol
Beta-2: Agonist potency rank: Iso>Epi>NE
- selective agonists: metaproterenol,
albuterol, ritodrine

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17
Q

What are dopamine receptors?

A

CNS and renal localization (Agonist selectivity: Dopamine»Epi)

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18
Q

What is the selective antagonist of B-1 receptors?

A

Metoprolol

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19
Q

What are the selective agonists for B-2 receptors?

A

Metaproterenol, Albuterol, Ritodrine

20
Q

What type of receptor does Norepinephrine work on?

A

A-1=A-2=B1»B2

21
Q

What are the cardiovascular actions of Norepinephrine? What is the change in cardiac output?

A
  • Increase TPR
  • Increase BP (increase in S and D)
  • Reflex decrease in HR
  • No change in CO (increase in SV due to increase in venous return and B-1 effects in ventricle)
22
Q

What is the formula for BP?

A

BP= HR x SV x TPR

- HR x SV= CO-

23
Q

What type of receptor does Phenylephrine work on?

A

A-1 agonist

24
Q

What are the cardiovascular actions of Phenylephrine?

A

Similar to NE (increase TPR, BP, decrease HR)

25
Q

What type of receptors do Epinephrine work on?

A

B-1=B2>A-1=A-2

26
Q

What are the cardiovascular actions of low dose of Epinephrine? High dose?

A
  • Decrease in TPR
  • Slight increase to no change in mean BP
  • Increase HR
  • Decrease renal and cutaneous flow
  • At high dose, like NE -
27
Q

What type of receptors does Isoproterenol work on?

A

B-1 and B2 agonists

28
Q

What are the cardiovascular actions of Isoproterenol?

A

Similar to lose dose Epi with subtle difference

- Slight decrease in mean BP due to greater decreases in TPR and DBP (but not enough to stimulate reflex)

29
Q

What type of receptors does Ephedrine work on?

A

Mainly indirect action but some direct (A and B agonists)

30
Q

What are the cardiovascular actions of Ephedrine?

A
  • Increase contractility
  • Increase HR at low/mod doses
  • High dose: Increase SBP, DBP, MBP with reflex bradycardia
31
Q

What other action does Ephedrine do?

A

Bronchodilation via B-2 in lungs

- Long duration of action

32
Q

What type of receptors does Albuterol work on?

A

B2 selective agonist

33
Q

What does Albuterol do?

A
  • Relaxation of airway smooth muscle

- are stimulated in vasculature with systemic administration

34
Q

What type of receptors does Dopamine work on?

A

Dopamine, B1 and alpha agonists

35
Q

What are the cardiovascular actions of Dopamine?

A
  • increase renal blood flow
  • Moderate dose: increase contractility and HR, increase CO, tachycardia less than isoproterenol
  • High dose: increase TPR
36
Q

What type of receptors does Dobutamine work on?

A

B1 and some A agonist

37
Q

What are the cardiovascular actions of Dobutamine?

A
  • Increase in contractility, HR, and CO (tachycardia less than iso)
  • High dose: Increase in TPR
38
Q

What type of receptors do Phenoxybenzazmine and Phentolamine work on? Which is irreversible?

A

non-selective alpha antagonists; Phenoxybenzamine irreversible

39
Q

What are the cardiovascular actions of Phenoxybenzamine and Phentolamine?

A
  • Decrease in TPR
  • Increase in BP in upright individual
  • No change or slight decrease in supine
  • Reflex increase in HR
40
Q

What are the adverse effects of Phenoxybenzamine and Phentolamine?

A

postural hypotension and tachycardia

41
Q

What type of receptors does Prazosin work on?

A

alpha 1 selective antagonist

42
Q

What cardiovascular actions act upon Prazosin?

A

Similar to non-selective drugs

- Less reflex increase in HR

43
Q

What type of receptors does Propranolol work on?

A

non-selective beta antagonists

44
Q

What are the cardiovascular actions on Propranolol?

A

B-1:
- Decrease HR, AV nodal conduction, contractility, CO
- Decrease renin release; decrease BP in hypertensive patient
B-2:
- acute increase peripheral vascular resistance
- increase airway resistance

45
Q

What are the adverse effects of Propranolol? Precautions?

A

(1) Cardiac depression
(2) Lassitude
(3) depression
- asthma and diabetes precautions

46
Q

What type of receptors does Metoprolol work on?

A

Beta 1 selective antagonists

47
Q

What are the cardiovascular actions of Metoprolol?

A

B-1:

  • Decrease HR, AV nodal conduction, contractility, CO
  • Decrease renin release; decrease BP in hypertensive patient
  • Little or no effect on airway resistance and peripheral vascular resistance

Pharmacology- Test 2 (10 decks)

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