Adrenergic Flashcards
(46 cards)
alpha agonist activity
Stimulation of a1
Induce contraction of smooth muscle
Primary effect- vasoconstriction of most vascular smooth muscle
alpha 1 selective agonist clinical use
Decongestant Pressor (BV constriction)
Phenylephrine important pharmokinetics
Longer duration of action than catecholamines
Phenylephrine (a1 agonist) adverse effects
Angina, anxiety, bradycardia, hypertension, tissue necrosis
alpha 1 and beta 1&2 agonists
sympathomimetics
alpha 1 and beta 1 &2 antagonists
sympatholytic
olol
beta blocker
lol
funny beta blocker
Phenylephrine interaction
MAO inhibitors (MAO breaks down phenylephrine)
Methyldopa is a
prodrug
a2 agonist action
Stimulation of a2 receptors in the medulla has sympatholytic effects
No reflex tachycardia
Decrease overall NE release thru stimulation of pre-synaptic receptors
Net Effect:
Hypotension
Bradycardia
Decreased cardiac output
a2 agonist clinical use
Hypertension
Clonidine more potent and used more often than methyldopa but pregnancy category C
Clonidine: Several CNS disorders including ADHD, mitigate drug withdrawal, severe pain
Methyldopa (a2 agonist) first-line therapy
for hypertension during pregnancy
a2 agonist adverse effects
orthostatic hypotension, tolerance, sudden withdrawal precipitates hypertensive crisis
Clonidine is effective both in the periphery and in the brain. Alpha-methyldopa is effective only in the
brain. It readily enters the brain where it is metabolized to the active compound a-methyl-norepinephrine (a2 agonist).
B1 effects in
heart, glomeruli cells in kidney
B2 effects in
lung (dialation), skeletal muscle vasculature (promotes blood flow)
Isoproterenol (nonselective B agonist) clinical use
cardiac arrest, AV block, bradycardia
Dobutamine
selective B1 agonist; activates a1 receptors at high doses; increases force of contraction of heart
B2 mech of action
(albuterol) Relaxation of vascular smooth muscle. Particularly in skeletal muscle vasculature Relaxation of bronchial smooth muscle. Stimulation of glycogenolysis May lead to hyperglycemia. Relaxation of uterine smooth muscle.
B2 agonist clinical use
Asthma
Acute bronchospasm
Bronchospasm prophylaxis
Premature Labor - Ritodrine (Yutopar®)
B2 agonist adverse effects
Tremors
Stimulation (CNS)
Palpitations
Tachycardia (direct and reflex) (some B1 effects)
a1 receptor location
blood vessels
a antagonists action
Block a1 or both a1 and a2 receptors
Decrease peripheral vascular resistance
Vasodilation triggers increased heart rate
HR increase more pronounced with mixed a1/a2 antagonists because of diminished a2 feedback in heart (remember a2 in presynaptic nerve termini).