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Neurotransmitters of the ANS
- acetylcholine (ACh)
- norepinephrine (NE)
- epinephrine (Epi)
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In the SNS preganglionic transmission is mediated by___
Ach
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In the SNS, postganglionic transmission is mediated by ____
NE
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adrenergic receptor types
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most frequent indication for adrenergic agonist drugs is_____
shock
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Adrenergic agonists
- mimic action of SNS
- stimulate adrenergic receptors
- 2 groups - catecholamines & noncatecholamines
- nonselective agonists stim both alpha & beta receptors
- prototype drug - EPINEPHRINE
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Ephinephrine indications (pharmacotherapeutics)
asthma, shock
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Epi pharmacodynamics
stim all adrenergic receptors and causes AEs in the cardiovasc syst & CNS
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Epi contraindications
hypersensitivity, sulfite sensitivity, glaucoma & use during labor
glaucoma b/c increased intraoc P could be made worse by inc BP (sympathetic effect of drug)
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Epi drug interactions
tricyclic antidepressants - when inc NE, dec effectiveness of antidepress
beta blockers - completely oppose agonist action
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which receptors are stim by Epi?
- alpha 1
- alpha 2
- beta 1
- beta 2
Epi is nonselective. the only receptor it does NOT stim is dopamine
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Alpha 1 adrenergic agonist
stimulate alpha-1 receptor directly
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Phenylephrine (Allerest)
A-1 Adrenergic agonist
- parenterally for vascular failure
- topically for relief of nasal mucosal congestion
AE= reflex bradycardia
Correct blood loss B4 administration
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sympathetic NS produces what type of response?
adrenergic
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parasympathetic NS produces what type of response?
cholinergic
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Alpha 2 adrenergic agonists
- stim alpha 2 receptors
- decrease symp outflow by inhib release of NE
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Beta adrenergic agonists
- mimic action of SNS
- prototype = DOPAMINE (Intropin)
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Inotrope drugs affect what?
muscle contractility
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chronotropic drugs affect what?
heart rate
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Dopamine
beta adrenergic agonist; stim dopaminergic receptors
corrects hemodynamic imablances in shock
stim a-1 and b-1 receptors so increases CO (pos inotrope)
AE= Ectopic beats, tachycardia (expected)
Tx effective if BP, urine output & CO return to normal
Only given IV
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Dopaminergic agonists
Stim DA1 & DA2 receptors - mediate responses in adrenergic NS
stim DA1 &2 results in periph vasodilation
stim both can have complementary or opposing effects
prototype= FENOLDOPAM
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fenoldopam (Corlopam)
short-term mgt severe hypotension
only binds with DA1 receptors
causes rapid vasodilation
AE = hypotension, reflex tachycardia
risk for hypokalemia
monitor BP to judge efficacy
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Alpha Adrenergic antagonists
block stim of alpha receptors
mediate prostatic smooth musc contraction
Prototype = PRAZOSIN
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prazosin (Minipress)
treats CHF, prostatic outflow (males only)
risk of orthostatic hypotension; monitor wt & check for edema d/t vasodilation
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beta adrenergic antagonists
stim of B1 only causes tachycardia
stim B1 & B2 causes vasodilation, decreased periph resistance and bronchodilation
prototype = METOPROLOL
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metoprolol (Lopressor, Toprol XL)
contraindicated w/antidepress - blocks NE which Antidepressants try to stim...can actually induce depression
AEs = hypoglycemia (SNS stim is blocked so pt wont even feel dec gluc effects)
do not abruptly stop med (have lots of open, sensitized receptors so BP skyrockets)
monitor BP, HR & edema
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Alpha-1 receptor effects
- inc periph resistance
- mydriasis
- vasoconstriction
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Alpha 2 receptor effects
- inhibition of lypolysis
- dec GI motility
- inhibition of NE release
- vasoconstriction
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Beta 1 receptor effects
cardiac effects
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Beta 2 receptor effects
- dec periph resistance
- vasodilation
- bronchodilation
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