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242 SEcTIoN II Pharmacology ` PHARMACOLOGY—AUTONOMIC dRUGS Pharmacology ` PHARMACOLOGY—AUTONOMIC dRUGS

Sympathomimetics
dRUG ACTION HEMOdYNAMIC CHANGES APPLICATIONS
Direct sympathomimetics
Albuterol, salmeterol, β 2 > β 1  HR (little effect) Albuterol for Acute asthma/COPD. Salmeterol
terbutaline for Serial (long-term) asthma/COPD.
Terbutaline for acute bronchospasm in asthma
and tocolysis.
Dobutamine β 1 > β 2 , α / BP,  HR,  CO Heart failure (HF), cardiogenic shock (inotropic
> chronotropic), cardiac stress testing.
Dopamine D 1 = D 2 > β > α  BP (high dose),  HR, Unstable bradycardia, HF, shock; inotropic and
 CO chronotropic effects at lower doses due to β
effects; vasoconstriction at high doses due to α
effects.
Epinephrine β > α  BP (high dose),  HR, Anaphylaxis, asthma, open-angle glaucoma;
 CO α effects predominate at high doses.
Significantly stronger effect at β 2 -receptor than
norepinephrine.
Fenoldopam D 1  BP (vasodilation),  HR, Postoperative hypertension, hypertensive crisis.
 CO Vasodilator (coronary, peripheral, renal, and
splanchnic). Promotes natriuresis. Can cause
hypotension and tachycardia.
Isoproterenol β 1 = β 2  BP (vasodilation),  HR, Electrophysiologic evaluation of
 CO tachyarrhythmias. Can worsen ischemia.
Has negligible α effect.

Midodrine α 1  BP (vasoconstriction), Autonomic insufficiency and postural
 HR, / CO hypotension. May exacerbate supine
hypertension.
Mirabegron β 3 Urinary urgency or incontinence or overactive
bladder. Think “mirab3gron.”
Norepinephrine α 1 > α 2 > β 1  BP,  HR, / CO Hypotension, septic shock.
Phenylephrine α 1 > α 2  BP (vasoconstriction), Hypotension (vasoconstrictor), ocular procedures
 HR, / CO (mydriatic), rhinitis (decongestant), ischemic
priapism.
Indirect sympathomimetics
Amphetamine Indirect general agonist, reuptake inhibitor, also Narcolepsy, obesity, ADHD.
releases stored catecholamines
Cocaine Indirect general agonist, reuptake inhibitor Causes vasoconstriction and local anesthesia.
Caution when giving β-blockers if cocaine
intoxication is suspected (can lead to
unopposed α 1 activation Ž extreme
hypertension, coronary vasospasm).
Ephedrine Indirect general agonist, releases stored Nasal decongestion (pseudoephedrine), urinary
catecholamines incontinence, hypotension.

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