Alpha and Beta Antagonists Flashcards
Alpha Adrenergic Antagonists are?
Phentolamine
Prazosin
Yohimbine
Phenoxybenzamine
Phenoxybenzamine binds how?
Covalently to the alpha receptor causing an irreversible blockade
Phentolamine, Prazosin,Yohimbine binds how?
Reversibly and is a competitive antagonist
Phenoxybenzamine and Phentolamine, work on which sites
Presynaptic Alpha 2 and Post synaptic Alpha 1
Prazosin works on which sites
Alpha 1
Yohimbine works on which sites
Alpha 2
Phentolamine effects Alpha 1 and 2 effects
A1 ->Peripheral vasodilation and decrease BP
A2->Increase in HR (Baroreceptor response) and CO
Phentolamine onset and duration
Onset 2 min
Duration 10-15 minutes
Phentolamine Alpha 1 and 2 effects
Alpha 1 -
Phentolamine use
Acute HTN emergencies with intra-op manipulation of Phenochromocytoma
Phentolamine Dose
30-70 mcg/kg continuous infusion
Phenoxybenzamine is a ?
Haloalkylamine derivative
Nonselective Alpha Blocker
Phenoxybenzamine onset
Slow 60 minute to peak effect
Phenoxybenzamine side effects
Orthostatic Hypotension
Impaired vasoconstriction with Large BP drop with blood loss or vasodilating drugs (Volitiles)
Phenoxybenzamine Clinical uses
BP control in Phenochromocytoma Pts
Excessive vasoconstriction in hemorrhagic shock
Yohimbine is a
Alpha 2 antagonist causing increased Norepi release
Yohimbine used to treat ?
Idiopathic Hypotension
Prazosin is a?
Alpha 1 antagonist
Prazosin dilates veins, arterioles or both
BOTH
The Gold standard of Beta blockers is ?
Propranolol
Chronic administration of Beta blockersis associated with ?
Up regulation of Beta receptors
Which Beta Blockers are Selective Beta 1 antagonists in normal doses?
Metoprolol, Atenolol, Esmolol
Bradycardia and myocardia depression are produce by Beta Blockers due to?
Blocking of the SNS to the heart
Beta 1 blockade causes?
Decrease HR and CO
Beta 2 blockade causes?
Increase Perif resistance including coronary resistance
Chronic Propranolol use can cause what with fentanyl?
Decrease pulmonary first pass uptake
Metoprolol A Beta 1 antagonist prevents
Increase in Inotropy and Chronotropy to Beta stimulation
Esmolol
Beta 1 selective
Given IV only
Esmolol Onset and Duration
Onset 5 min
Duration 10-30
Esmolol elimination
Plasma esterases
Esmolol Dose
0.2-0.5 mg/kg IV
Beta Blocker can
Cross the BBB and Placenta
Alters airway resistance
Beta Blocker contraindication
Existing AV block or Heart Failure.
Not Recommended for COPD Pts
May mask Hypoglycemia
Cardiovascular effects of Beta Blockers reflect SNS innervation removal to the heart. AKA
Beta 1 Blockade
NON selective Beta Blockers result in Beta 2 Blockade causing unopposed ?
Alpha 1receptor peripheral vasoconstriction
Beta Blocker OD treatement
Atropine 7 mcg/kg
Dobutamine if a pure BB Present
Glucogon 1-10 mg IV (DRUG OF CHOICE)
Beta 2 Blockers increase airway resistance T/F?
TRUE
Clinical Uses Of Beta Blockers?
Treatment of HTN Angina Post MI Pre-op prep for Hyperthyroid Prevention of excessive SNS activity Suppression of cardiac dysrhythmias
Labetalol is a ?
Alpha1 and Beta 1,2 Antagonist ( Blocker)
Labetalol Dose
0.25 mg/kg
Labetolol lowers BP by decreasing SVR Alpha 1 Blockade and prevents reflex tachycardia by ________?
Beta 1 blockade
Labetalol does not change?
CO
Labetalol side effects
Orthostatic Hypotension
Bronchospasms
CHF, Bradycardia, heart block
