Adrenergic Blockers Flashcards
Adrenergic β- Blockers have what result on ⍺ responses?
⍺ processes become dominant
reverse true for ⍺-Blockers?
Normal result of ⍺1 stim?
Excitatory: mydriasis (C radial mm) C bv to skeletal mm, skin C hold urine ejaculation
Normal result of ⍺2 stim?
Inhibitory:
↓ NE release
↓ insulin secretion
R GI
⍺1-Blockade causes?
(Decreased vasoconstriction) ↓ peripheral resistance -> ↓ BP ↓ venous return (ortho/standing hypoTN) Miosis Nasal congestion ↑ urine flow (tx BPH) ↓ ejaculation
⍺2-Blockade causes?
↑ NE release
↑ insulin release
Normal results of β1 stim?
Inhibitory:
↑ renin
↑ HR, cond, contr
Normal results of β2 stim?
Inhibitory: R bronchioles R bv in skeletal mm R coronary/cerebral arteries (↑ HR, cond, contr) R GI/U ↑ glycogenolysis/genesis
Normal results of β3 stim?
Inhibitory:
↑ lipolysis
β1-Blockade causes?
↓ renin
β2-Blockade causes?
Bronchoconstriction
↓ rate/force contraction = ↓ CO, ↓ O2 demand
↓ IO pressure
↓ glycogenolysis
β3-Blockade causes?
↓ lipolysis
Competitive ⍺ agonsists shift dose-response curve?
Right (need more NE to cause effect)
Max effect is same
Competitive ⍺ agonsists duration dependent on? (2)
dissociation from receptor
1/2 life
Irreversible ⍺ agonsists shift does-response curve?
Right
Max response diminished
Irreversible ⍺ agonsists duration dependent on?
exceed 1/2 life (stays bound)
Reflex tachycardia results from ⍺-Blockade why? (2)
1) ↓ BP -> stim baro -> stim sypathetics (↓ vagal input)
2) ⍺2 block -> ↑ NE release -> ↑ β heart stim
Ortho HTN results from ⍺-Blockade why?
⍺1 block = ↓ vasoconstriction of veins
↓ contraction -> ↓ filling pressure -> ↓ BP
EpiNE reversal of ⍺-Blockade?
blocked ⍺ exposes β:
Epi dilates bv to skeletal mm ->
↓ BP -> reflex ↑ HR
Phentolamine (Regitine) affects what receptors?
⍺1 and ⍺2
Phentolamine effects on ⍺1?
(⍺-block)
↓ peripheral resistance -> ↓ BP
Phentolamine effects on ⍺2?
(⍺-block)
↑ NE = ↑ baro -> cardiac stim (β)
Phentolamine side-effects?
HypoTN
Tachycardia
Arryth
myocard ischemia
Phentolamine used to tx?
HTN from pheonchromocytoma or MAO inhibitors
necrosis post ⍺-agonist infusion
Phentolamine contraindicated for?
CAD peptic ulcers (stims histamine = acid prdxn)
Phenoxybenzamine affects what receptors?
IRREVERSIBLE ⍺-block
Phenoxybenzamine effects on ⍺ receptors?
(lasts several days)
↓ BP -> reflex tachycardia
⍺1 block = ↓ vasoconstriction -> ortho hypoTN
⍺2 block = inhibit NE reuptake
Phenoxybenzamine side-effects?
tachycardia
ortho hypoTN
nasal congestion
↓ ejaculation
Phenoxybenzamine used to tx?
pheochromocytoma (high symp tone),
irreversible binding prevents HTN
Phenoxybenzamine contraindicated?
hypovolemic,
alcohol use,
vasodilators
= severe hyopTN
Pheochromocytoma is?
adrenal neoplasm:
releases NE/Epi
Pheochromocytoma signs/sxs?
tx?
sudden-onset severe HTN, tachycardia, arrhy
Phenoxybenzamine
surgery
Prazosin affects what receptors?
⍺1 antagonist
Prazosin effects on ⍺1?
relax artery/vein smooth mm ->
↓ peripherial resistance,
↓ venous return/preload
no effect on ⍺2 means:
No ↑ CO
No tachycardia reflex
No NE increase
Prazosin administered?
1/2 life?
orally
3 hrs (doubles if CHF)
Prazosin side-effects?
1st dose phenom:
ortho hypoTN/syncope 90 mins post dose
nasal congestion
ortho hypoTN, esp w/ viagra
Prazosin used to tx?
HTN
BPH
Other drugs similar to Prazosin?
Terazosin, Doxazosin
longer 1/2 lives = once daily dose
Tamsulosin (Flomax) affects what receptors?
(Antagonist)
⍺1A (prostate)
⍺1B (bv)
has very little effect on BP
Tamsulosin used to tx?
BPH (relaxes urinary sphincter)
low BP effects makes good alternate is “zosins” cause ortho hypoTN
Yohimbin affects what receptors?
Causes?
⍺2 antagonist
↑ NE release (CNS/periphery) ->
↑ symp tone -> ↑ BP and HR
Yohimbin used for?
“natural” viagra
Yohimbin contraindications?
interferes w/ Clonidine
pts w/ HTN
Short term β-Block vs long term β-block effect on BP?
short = ↑ BP
long = ↓ BP
Effect of exercise/stress on HR when taking β-Block?
HR can’t ↑ as much
β-block effect on EpiNE?
↑ pressor effect (vasoconstriction/↑ BP) due to block of 2 dilators
**don’t give for pheochromocytoma w/o ⍺-block too
Danger of β-block effect on glycogenolysis?
↓ glycogenolysis masks and impairs tx of hypoglycemia
Propranolol (Inderal) affects what receptors?
β1 and β2
competitive antagonist
Propranolol effects on β1 and β2?
competitive antagonist: ↓ HR, force, conduction ↓ renin ↓ glycogenolysis ↓ lipolysis local anesthetic
Propranolol administered?
Metabolized by?
Soluble to CNS?
oral but variable 1st pass metabolism (wide dosage)
liver
yes
Propranolol used to tx?
↓ mortality from MI Angina (↓ O2 demands) Obstructive cardiomyopathy (antiarrhythmic) Early CHF Migraine stage fright
Propranolol side-effects?
Bronchoconstriction (ø asthma or COPD) Bradycardia Abrupt disuse -> arrhythmia (up-regulated β rec) Worsen Late CHF sedation, depression (CNS)
Propranolol drug interactions?
drug that inhibit P450 = ↑ hypoTN
(Cimetidine, chlorpromazine)
drug that speed metabolism = ↓ effectiveness
(smoking, barbituates, rifampin)
Ca2+ channel blockers = additive effect
Timolol affects what receptors?
all β
antagonist
Timolol primary use?
treat glaucoma
Timolol caution?
absorbed systemically so ø asthmatics
Nadolol affects what receptors?
all β
antagonist
Nadolol benefits over other non-specific β-blokers?
no CNS penetration
no local anesthesia
less variability of absorption
long-acting
Sotalol affects what receptors?
all β
antagonist
Sotalol benefits over other non-specific β-blokers?
blocks K+ channels
no local anesthetic
antiarrythmic
Effects of β1-selective Antagonists w/o Intrinsic Sympathetic Activity?
Mostly heart:
↓ HR, force
Benefits of β1-selective Antagonists w/o Intrinsic Sympathetic Activity?
ø block of bv dilation in skeletal mm = better exercise tolerance
less inhibition of glycogenolysis = ↓ hypoglycemia risk (safer for DM)
β1-selective Antagonists w/o Intrinsic Sympathetic Activity use to tx?
HTN
Migraine prophylaxis
Post MI»_space; life
Glaucoma (Betaxolol only)
β1-selective Antagonists w/o Intrinsic Sympathetic Activity side-effects?
bradycardia
hypoTN
(P) develop DM II
C/I asthmatics, COPD
β1-selective Antagonists w/o Intrinsic Sympathetic Activity drugs? (3)
Metroprolol (Lopressor) Atenolol (Tenormin) Bisoprolol (Zebeta) Betaxolol (Betoptic) Nebivolol (Bystolic) Esmolol (Brevibloc)
Benefits of Nebivolol over other β1-selective Antagonists w/o Intrinsic Sympathetic Activity drugs?
↑ NO release from endo cells = vasodilator,
MOST selective for β1,
↓ arterial BP w/o depressing LV fxn,
Better ↓ of central aortic pressure,
Signification ↓ cholesterol, trigly, glucose
Fewer s/e
Benefits of Esmolol over other β1-selective Antagonists w/o Intrinsic Sympathetic Activity drugs?
Very short duration (1/2 life 8 min)
IV
Use for urgent need for rapid effects
Intrinsic Sympathetic Activity (ISA) means what?
PARTIAL AGONIST activity:
stim receptors when symp activity low,
reduce effects when NE/Epi is high
β-NON-selective Antagonists with Intrinsic Sympathetic Activity (ISA) drugs?
Pindolol (Visken)
Carteolol (Cartrol)
Penbutolol (Levatol)
β1-selective Antagonist w/ ISA drug?
Acebutolol (Sectral)
β-Antagonists ISA drugs used to tx?
HTN
Angina
Glaucoma (Carteolol)
β-Antagonists ISA drug benefits?
less - effects on plasma lipids?
(P) less bronchocon, bradycard
Labetalol affects what receptors?
⍺1, β1, β2
blocker
Labetalol effects on ⍺1?
β1?
↓ peripheral vascular resistance
prevents reflex ↑ HR (tachycardia)
Labetalol use to tx?
HTN
HTN emergencies
Carvedilol affects what receptors?
⍺1, β
blocker
Carvedilol effects on ⍺1?
β?
↓ peripheral vascular resistance
prevents reflex ↑ HR (tachycardia)
Carvedilol used to tx?
HTN
CHF
post MI
Guanethidine (Ismelin) affects neurotransmitters how?
Method of action?
inhibits release of NE from terminal
replaces NE stores in vesicles
Guanethidine effects inhibited by what type of drugs?
uptake inhibitors:
TSA, cocaine
Guanethidine s/e?
complete loss of sympathetic activity:
severe hypoTN
↓ blood to brain/heart
Reserpine affects neurotran how?
Results in?
interefers w/ uptake and storage
depletion of NE, DA, serotonin in periphery/brain
Reserpine s/e?
sedation, depression, parkinson’s sxs
Metyrosine (Demser) affects neurotrans how?
Results in?
blocks synthesis of DA (blocks tyrosine hydroxylase enz)
↓ NE, Epi
Metyrosine used for?
pre-surg and inoperable pheochromocytoma