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Flashcards in Sympathetic antagonists Deck (13):
1

Phenoxybenzamine

  • MOA
    - irreversibly blocks α1 and α2 
    - indirect baroreflex activation
  • Effects
    - lowers BP
    - HR rises due to baroreflex activation
  • Clinical 
    - pheochromocytoma/high catecholamine states
  • Kinetics, tox, int.
    - irreversible blocker, duration>1 day
    - tox: orthostatic hypotension, tachycardia, myocardial ischemia

2

Phentolamine

  • MOA
    - reversibly blocks α1 and α2 
  • Effects
    - blocks α-mediated vasoconstriction, lowers BP, increases HR (baroreflex)
  • Clinical
    - pheochromocytoma
  • Kinetics, tox, int. 
    - t1/2 approx 45min after IV injection

3

Prazosin, doxazosin, terazosin

  • MOA
    - block α1 but not α2 
  • Effects
    - lower BP
  • Clinical
    - hypertension
    - benign prostatic hyperplasia
  • Kinetics, tox, int.
    - larger depressor effect with first dose may cause orthostatic hypotension

4

Tamsulosin

  • MOA
    - slightly selective for α1A 
  • Effects
    - may relax prostatic smooth muscle more than vascular smooth muscle
  • Clinical 
    - benign prostatic hyperplasia 
  • Kinetics, tox, int. 
    - orthostatic hypotension less common with this subtype

5

Yohimbine

  • MOA
    - blocks α2 
    - elicits increased central sympathetic activity 
    - increased norepinephrine release
  • Effects
    - raises BP and HR
  • Clinical
    - male erectal dysfunction
    - hypotension
  • Kinetics, tox, int. 
    - may cause anxiety
    - excess pressor effect if norepinephrine transporter is blocked

6

Labetalol

  • MOA
    - β>α1 block
  • Effects
    - lowers BP with limited HR increase
  • Clinical
    - hypertension
  • Kinetics, tox, int.
    - oral, parenteral
    - tox: less tachycardia than other α1 agents

7

Propranolol, nadolol, timolol

  • MOA
    - block β1 and β2 
  • Effects
    - lower HR and BP
    - reduce renin
  • Clinical 
    - hypertension, angina, arrythmias, migraine, hyperthyroidism, glaucoma
  • Kinetics, tox, int. 
    - oral, parenteral
    - tox: bradycardia, worsened asthma, fatigue, vivid dreams, cold hands

8

Metoprolol, atenolol, betaxolol, nebivolol

  • MOA
    - block β12 
  • Effects
    - lower HR and BP
    - reduce renin
    - may be safer in asthma 
  • Clinical
    - angina, hypertension, arrythmias, glaucoma
  • Kinetics, tox, int.
    - tox: bradycardia, fatigue, vivid dreams, cold hands

9

Butoxamine

  • MOA
    - blocks β21 
  • Effects
    - increases peripheral resistance
  • Clinical 
    - no clinical indication
  • Kinetics, tox, int.
    - tox: asthma provocation

10

Pindolol, acebutolol, carteolol, bopindolol, oxprenolol, celiprolol, penbutolol

  • MOA
    - β1, β2, with intrinsic sympathomimetic (partial agonist) effect
  • Effects
    - lower BP
    - modestly lower HR
  • Clinical 
    - hypertension, arrythmias, migraine, may avoid worsening of bradycardia
  • Kinetics, tox, int. 
    - oral
    - tox: fatigue, vivid dreams, cold hands

11

Carvedilol, medroxalol, bucindolol

  • MOA
    - β>α1 block
  • Effects 
    - same as labetalol? 
  • Clinical
    - heart failure
  • Kinetics, tox, int. 
    - oral, long t1/2 
    - tox: fatigue 

12

Esmolol

  • MOA
    - β12
  • Effects
    - very brief cardiac β blockade
  • Clinical
    - rapid control of BP and arrythmias
    - thyrotoxicosis
    - myocardial ischemia intraoperatively
  • Kinetics, tox, int. 
    - parenteral only, t1/2 approx 10 min
    - tox: bradycardia, hypotension

13

Metyrosine

  • MOA
    - blocks tyrosine hydroxylase
    - reduces synthesis of dopamine, norepinephrine, and epinephrine
  • Effects
    - lowers BP
    - may elicit extrapyramidal effects (due to low dopamine in CNS)
  • Clinical
    - pheochromocytoma
  • Kinetics, tox, int. 
    - tox: extrapyramidal symptoms, orthostatic hypotension, crystalluria