Adrenergic Antagonists Flashcards
Reversible Alpha Receptor Antagonists
compete w.agonists and endogenous catecholamines
blocks receptor and can dissociated if agonist is present in high amounts
duration depends on drugs affinity for receptor and the drugs 1/2 life
irreversible Alpha Receptors
covalent bonds (permanently block) longer 1/2 life duration of action dependent in synthesis of new receptors
Alpha Antagonists on CV system
block alpha 1 vasoconstriction=vasodilation=drop in BP
reflex tachycardia develops in response to maintain CO
Other Effects of Alpha 1 antagonists
block mydriasis (get miosis=constriction) block nasal vasoconstriction=congestion block urinary retantion=facilitates urination
Phenoxybenzamine (Dibenzyline)
alpha antagonist
irreversibly blocks alpha 1
causes vasodilation
also blocks presynaptic alpha 2 receptors
tx Pheochromocytoma
excessive catecholamine release (oversecretion of NE and Epi)
Phentolamine (OraVerse)
alpha antagonist
Reversibley blocks Alpha 1 and presynaptic alpha 2
a1 block=decrease BP
A2 block=increase cardiac stimulation
tx pheochromocytoma
Prazosin (Minipress)
alpha 1 antagonist
tx HTN
Terazosin (Hytrin)
alpha 1 antagonist
used to tx HTN
Doxazosin (Cardura)
alpha 1 antagonist
used to tx HTN
Tamsulosin (Flomax)
alpha 1 agonist
tx HTN and relax smooth muscle of prostate to tx BPH=allows urination
Beta Receptor Antagonists
bind reversibly
drugs differ in affinity and selectivity for blocking Beta 1 and Beta 2 receptors
selectivity decreases with higher dose
Beta antagonists on cardiovascular system
“beta blockers”
tx HTN in pt that also has angina, CHF, MI
reduces cardiac work loads (-inotropic and - chronotropic)
slows AV node and decreases HR
Beta Blockers and BP
block Beta 2 receptors=Bp decreases
enhanced by agents that also bock alpha 1 receptos–>labetolol`
Beta Blocker use in Angina
imprives balance between oxygen supply and demand.
Block adrenergic=reduction in cardiac work load
Contraindication of Beta blocker use in Pt’s with asthma and COPD
B blcokers are not selective, so beta blcokers can worsen asthma and COPD because b2 antagonists can cause bronchoconstriction
Beta Blocker use in Ophthamic
tx open angle glaucoma
reduces production of aqueous humor
Other effects of Beta Blockers
block glucose metabolization
worsen high cholesterol
local anesthertic
Metabolic Effects of Beta Blockers
block glucose metabolizm-blocks bodys ability to make glucose available when needed–>complications with IDDM
Cholesterol Issues with Beta Blockers
increases VLDL (bad) and decreases HDL (good)
Intrinsic Sympathomimetic Activity (ISA)
when beta blockers has beta agonist activity
may decrease theraputic effects and also decrease negative side effects
labetolo
pindolol
acebutolol
Local Anesthetic Actions of Beta Blockers
blocks sodium cannels-blocks abulity of pain stimulus to get to brain acebutolo labetolol pindolol propranolol
Beta Blockers to tx HTN
1st lines in pt's with heart failure, post MI, angina, DM atenolo (tenormin) bisoprolol (zabeta) metoprolol (lopressor, toprol) nadolol (corgard) Pindolol (visken)
Beta Blockers to tx Ischemic Heart Disease
b blcokers=decrease cardiac work load=less demand for o2
1st line in pt’s at risk for MI or have hx of angina or left ventricular dysfunction
Propranolo (Inderal)
metoprolol (lopressor)
Beta Blockers to tx Arrhythmias
tx ventricular and svc tachycardia, a fib and atrial flutter
b blockers slow down heart rate
metoprolol (lopressor), sotalol (betapace)
Beta Blockers and Heart Failure
Chronic heart failure
metoprolol (lopressor)
bisoprolol (zabeta)
carvedilol (coreg)
Beta Blockers used in Glaucoma
local acting decreases production of aqueous humor timolo (timoptic) bextaxolol (betoptic) carteolol (ocupress) levobunolol (betagan)
Beta Blockers use in Hyperthyroidism
b blockers block adrenergic receptors (decreases symptoms), decreases conversion of T4 to T3 which
propranolol
Beta Blockers use for Migraine headaches
metroprolol, propranolol, reduce frequancy or intensity of migraines
beta Blockers use in performance anxiety
slows heart rate, reduces palmar sweating
Beta Blockers in hepactic dieases
specific beta blockers can target effect to reduce elevated blood pressure
Nadolo (corgard)
Propranolol (Inderal)
Unwanted Effects of Beta Blockers
bradycardia
worsening of asthma
may worsen CO in pt’s with heart failure
exacerbate hypoglycemia in IDDM’s
