Much of the same action as anticholinergics, except
these drugs are more specific and have a wider
therapeutic application.
Catecholamines: Same structure as NE, shorter
duration of action
Must be given parenterally
Noncatecholamines: Not rapidly destroyed by MAO
or COMT, so longer duration of action
Can be given orally
Most act directly by binding to and activating adrenergic receptors, but
some act indirectly by causing release of NE or by inhibiting reuptake or
destruction of NE
Effects are predictable based on which
receptor subtype is stimulated. Here's what they treat:
Alpha 1: Nasal congestion, hypotension,
mydriasis for ophthalmic exams
Alpha 2: Hypertension
Beta 1: Cardiac arrest, heart failure, and
shock
Beta 2 receptor: Asthma and premature
contractions
Beta 3: Overactive bladder
Side effects such as tachycardia,
hypertension, dysrhythmias may
limit therapy
CNS excitement and seizures can occur
at a large dose
Dry mouth, nausea, vomiting, and anorexia
can also occur
Alpha-adrenergic agonists: Used for effects on vascular
smooth muscle
Relaxes vascular
smooth muscle in
small arteries, causing
vasodialtion and
decreasing blood
pressure
Can cause orthostatic
hypotension, reflex
tachycardia, nasal
congestion, and
impotence
Phentolamine is
used to diagnose
pheochromocytoma
(pg.151)
Greater therapeutic application.
Similar effect to parasympathomimetics
Treatment of hypertension
Beta-adrenergic agonists: Decrease rate and force of heart
contraction and slow electrical conduction through AV
node
Used primarily for hypertension, but
can also work for migraines, angina
pectoris, dysrhythmias, heart failure,
MI, and narrow angle glaucoma
May exacerbate heart failure in some patients.
Increases risk of hypotension and bradycardia. Can
cause bronchial constriction, hypoglycemia,
diarrhea, nausea, vomiting, muscle cramps, rash,
blurred vision, fatigue, depression, and erectile
dysfunction
Abrupt discontinuation can
cause acute resurgence of
symptoms.