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21 Cards in this Set
- Front
- Back
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Alpha Adrenergic Receptors
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Potency Series: Epi > Norepi > Isoproterenol
a1: vascular smooth muscle (vasoconstriction) a2: adrenergic nerve terminals (dec. NE release) |
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Beta Adrenergic Receptors
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Potency Series: Isoproterenol > Epi > Norepi
B1: heart (Inc. HR, contractility) B2: lung, vascular smooth muscle (vasodilation) |
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Where do adrenergic agonists and antagonists work?
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At the post-synaptic receptor
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Cocaine and tricyclic antidepressants
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Block re-uptake of NE
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Amphetamines
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Cause NE release (stimulation of the nerve itself)
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Potency
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Increased potency = Increased affinity for receptor
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Biosynthesis and release of catecholamines at the adrenergic nerve terminal
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Tyrosine -> DOPA -> dopamine -> NE
Tyrosine -> DOPA = rate-limiting step |
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What happens when NE is released into the cleft? How do you get rid of it?
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1. re-uptake mechanism: transports neurotransmitter back into nerve terminal
2. MAO: breaks down NE into metabolites |
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Adrenergic Receptor Agonists (sypathomimetics)
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Phenylephrine
Norepinephrine Epinephrine Isoproterenol |
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Phenylephrine (Neo-Synephrine)
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Receptor: a1
Action: Increase in total peripheral resistance leads to increase in BP Reflex: Decrease HR Use: Decongestant, hypotension |
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Norepinephrine (Levophed)
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Receptor: alpha, beta1
Action: Inc. peripheral resistance -> inc. BP Reflex: Dec. HR, Inc. contractility (B1) Use: Hypotension, shock |
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Epinephrine (Adrenalin)
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Receptor: B1, B2 (alpha only at high dose)
1. Inc. systolic BP (inc. contractility, B1) 2. Dec. diastolic BP (dec. total per resis, B2) 3. Increase HR (B1) Use: Cardiac arrest, shock, topical gum retraction, co-administered w/ local anesthetic (confines and inc. duration) |
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Isoproterenol (Isuprel)
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Receptor: B1, B2
1. Inc. systolic BP (inc. contractility, B1) 2. Dec. diastolic BP (dec. peripheral resistance, B2) 3. Inc. HR (B1) Use: heart block, cardiac arrest |
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Adrenergic Receptor Alpha-Blockers
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Phentolamine
Prazosin |
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Phentolamine (Pegitine)
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1. Nonselective alpha-antagonist: blocks a1 and a2
2. decrease peripheral vascular resistance 3. decrease BP 4. reflex tachycardia Use: Pre-surgery control of BP with pheochromocytoma Adverse Effects: postural hypotension, reflex tachycardia |
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Prazosin (minipress)
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1. Selective a1 blocker
2. Decrease peripheral vascular resistance 3. Decrease BP 4. Less reflex tachycardia than nonselective antagonists (Phentolamine) Use: hypertension, benign prosthetic hyperplasia Adverse Effects: hypotension related (dizziness, fatigue) |
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Adrenergic Receptor Beta-Blockers
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Propanolol and Metoprolol
- block symp. receptors - no reflex tachycardia 1. dec. HR, contractility, CO = dec. BP 2. Dec. renin release, dec. angiotensin II formation = dec. BP Use: anti-hypertensive, anti-anginal, anti-arrhythmic Adverse Effects: Sedation, Cardiac suppression, impotence (males) Precautions: asthma, diabetics |
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Propanolol (Inderal)
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beta-1 and beta-2
Do NOT use on asthma patients |
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Metoprolol (Lopressor)
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Selective beta-1 blocker
Ok to use on asthma patients |
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Adrenergic Antagonists and Dentistry
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alpha and beta blockers: syncope on standing
Epi reaching the systemic circulation in patient on nonselective beta-blocker can precipitate dangerous elevation in BP |
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Adrenergic Agonists and Dentistry (Epi)
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To high dose can lead to tissue ischemia and necrosis (intense vasoconstriction). Potential to reach systemic circulation.
Precautions: If patient has underlying cardiovascular disease, may cause inc. BP, inc. HR and cardia arrhythmias |
