Alpha and Beta Receptor Antagonist Flashcards
blocking alpha 2 receptor will have a similar effect as ___________ the beta receptor.
stimulating
List the effect of beta 2 agonist on : Blood vessels Bronchioles Uterus Kidneys Liver Pancreas
Blood vessels-dilation Bronchioles-dilation Uterus-Relaxation Kidneys-Renin secretion Liver-Glycogenolysis+Gluconeogenesis Pancreas-insulin secretion
What are the effects of alpha 1 activation on :
Bklood vessles
Pancreas
Intestine and bladder
Blood vessels-constrict
Pancreas-inhibition of insulin secretion
Intestine and bladder: Relaxion + constriction of sphincters
What are the effects of alpha 2 activation on:
postganglionic/presynaptic nerve ending
CNS (presynaptic)
Platelets
Postganglionic: Inhibition of norepi release
CNS: Increase of K+ conductance
Platelets: aggregation
What are clinical uses of alpha antagonism?
Tx of: pheochromocytoma CHF BPH Raynauds
What are the effects fo alpha 2 blockade?
Increased sympathetic outflow and increased release of epi from nerve endings
What are the effects of alpha adrenergic receptor antagonists. What are side effects?
Binds selectively to alpha receptors to block effects of catecholamines at receptor sites
Causes orthostatic hypotension and syncope
Reflex tachycardia
Impotence
What are uses for phentoalamine.
Phentoalamine is a competive nonselcetive alpha antagoinst used to treat acute hypertensive emergencies s.a. pheochromocytoma or autonomic nervous system hyperreflexia.
Alpha 1 blockade causes decrease in Systemic BP, reflex tachycardia
Apha 2 blockade causes a release of norepi increasing HR and CO. It also gives a parasympathetic response s.a. abdominal pain and diarrhea
What kind of drug is prazosin? How does it work? What are its uses?
Prazosin is an alpha 1 selective competive alpha antagonist
Its effects: less likely reflex tachycardia
Dilates both art and venous
Primarily antihypertensive
Used for preop bp in pheochromocytoma and in reynauds and BPH
How do taxazosin and tamulosin work?
Act preferentially on alpha-1 receptors of vesical trigone muscle, urethra, and prostate
Relax prostatic smooth muscle to tx BPH
Where does yohimbine work?
What is its clinical use?
Selective antagonist at presynaptic alpha 2
Increases release of norepi
Used as a tx for idiopathic orthostatic hypotension
Tx for impotence
Too much causes tachycardia and hypertension
HOw does phenoxybenzamine interact with the receptor?
What is duration of action?
Non competitive (irreversible) nonselective alpha blocker Alpha 1 > alpha 2 Lasts for 14-48 hours or longer
What are the uses for phenoxybenzamine?
Used as preop tx for pts with raynaud’s or pheochromocytoma
Prevents inhibitory action of epi on secretion of insulin
Causes orthostatic hypotension
What are the cardiovascular uses of beta blockers?
Treatment of essential hypertension Management of Angina Pectoris Treatment of Acute Coronary Syndrome Perioperative Beta blockade Treatment of Intraoperative myocardial ischemia Supression of Cardiac Dysrythmias Mangagement of Congestive Heart Failure Preop prep of hyperthyroid
Beta blocker therapy should be continued thru the periop period. t/f
T
What are two strategies to prevent/treat cardiac ischemia?
Minimize cardiac O2 demand
Maximize O2 supply
What are uses of beta blockers that are not cardiac related?
prevention of primary and secondary digestive bleeding in portal hypertension by rupture of esophageal varices
treatment of migraine, tremor, transitory somatic symptoms of anxiety, alcohol addiction in which there appears a beta overstimulation
treatment of glaucoma by ophthalmic solutions
Beta blockers are competitive inhibitors. What determines whether partial or full antagonism?
What drug would be used to overcome beta blockers?
Competitive inhibition over come by atropine
Partial or full antagonist based on intrinsic sympathomimetic activity
Beta blocker receptor selectivity is _______ dependent
Dose
What are the CV side effects of beta blockers?
(-) iontropic and chronotropic
AV node conduction decrease
Accentuates AV block–may increase to a 3rd degree block
(AV blocks are a contraindication to prescription)
Beta blockers may increase concentrations of local anesthetics and fentany T/F?
T
B blockers bind to albumen and kicks the other stuff off
How do beta blockers affect MAC?
decrease
Beta blockers may ________ triglycerides and ________ glucose.
increase triglycerides and cause hypoglycemia.
A rebound in symptoms may occur at abrupt discontinuation
Beta blockers should be continued during lactation. T/F
False, they are contraindicated in lactation
Beta blockers are good for Aortic ________, but bad for Aortic _______.
Good-aortic stenosis
bad-aortic insufficiency
Why would a beta blocker be bad in anaphylactic shock?
Epi is tx.
Propanolol may cause retention of which electrolyte?
Na
Propanolol is a selective B1 antagonist. T/F
False-nonselective
Propanolol decreases HR, Contractility and CO. Decrease in HR lasts longer than contractility. T/F
T
Which nonselective Beta blocker has a 20-40 huour half life?
nadolol
Which nonselective Beta blocker is used to treat glaucoma?
Timolol
What are the effects of Satolol? What can it be used to treat? What is the potential problem?
prolongs cardiac action potental
Increases refractory period
Used to Tx SVT
Since it prolongs Q-T it may lead to V-tach
What is the most selective B1 antagonist?
Atenolol
What are the effects of metoprolol? What is the dose?
negative chronotropy and ionotropy
Dose dependent selectivity
IV dose is 1-2 mg
How is esmolol metabolized? What is the elimination half life?
hydrolysis by plasma cholinesterase
Elimanation half life is 9 minutes
–works in 5 min done in 10-30
What is the bolus dose of esmolol?
- 5mg/kg iv
0. 1-0.3mcg/
How does labetolol affect receptors?
Alpha1 and noselective B1 and B2 antagonist
Beta:Alpha 3:1 oral
7:1 IV
What are the effects of labetalol?
Decreases SVR HR decrease Reflex tachycardia blocked CO unchanged May be used in pheo Beware: asthmatics
What is the dose of lablatolol? What is the onset, duration and elimination half time?
.1-.5mg/kg
works in 5-10 minutes
Elimination time is 5 hours
What are the effects of carvedilol?
Beta antagonist activity with alpha1 antogonist activity
Tx of pts with essential hypertension
Causes both precapillary vasodilation bymeans of alpha1 blockade and nonselective B blockade and devoid of intrinsic sympathomimetic activity
What are the most common adverse reactions to carvedilol?
edema, dizziness, bradycardia, hypotension, nausea, diarrhea and blurred vision
What is the ratio of beta: alpha1 blockade in carvedilol?
10:1
What are the effects of alpha-2 agonists?
Norepi inhibition
sympatholytic
anesthetci adjuvant
analgesia for acute and chronic paine
What are effects of Clonidine?
alpha 2:alpha 1 200:1
Antihypertensive–withdrawl can precipitate hypertensive crisis
can be given neuraxially
Other uses: Anti emetic, sedation
What properties do dexmedetomidine posess?
Anxiolytic, anesthetic, hypnotic and analgesic–thru specific and selective postsynaptic alpha2 adrenoreceptors
What are the side effects of dexmedetomidine?
Hypotension and bradycardia
Use with caution in hypovolemic, hypotensive, or elderly
Also: advanced heart block, severe ventricular dysfunction, DM or chronic HTN
Pts receiving dexmedetomidine infusions are _____ aroused, calm and comfortable.
easily
What are teh benefits fo precedex over currently available sedative agents?
lack of resp. depression
decreases need for opioid analgesiscs
Pts on chronic beta blocker therapy must be given beta blocker within ____ hours of surgery
24
For cardiac cases, most pts should be given a beta blocker dose within 6 hours of surgery. T/F
F
all pts regardless of preop regimen MUST be given beta blocker within 6 hours of surgery
beta blockers are contraindicated in which heart pts?
AV blocks
