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