Adrenergic Agonists

Alpha 1 receptors

cause smooth muscle contraction (mydriasis, vasodilation)

Alpha 2

inhibits neurotransmitter release at presynaptic nerve terminals

Beta 1

acts on the heart increaseing HR, conduction, and force of contraction; causes renin release from kidney

Beta 2

acts on the lungs causing dilation of arterioles and bronchi; enhanced glycogenolysis in the liver

alpha receptor result

Better vision

Increased BP

Blood redirected to essential functions

Beta receptor result

Increased HR

Improved Oxygenation

Glucose breakdown for energy

Renal perfusion

Catecholamine Adrenergic Agonists

Drugs that stimulate and mimic the actions of the sympathetic nervous system

Catecholamine metabolism

Polar; metabolized by enzymes MAO and COMT in intestines and liver; must be given parenterally

Epinephrine

Nonselective adrenergic agonist; Stimulates all alpha & beta receptors

Epinephrine therapeutic uses

Anaphylactic shock

Cardiac Arrest

V-Fib

Asthma

Vasoconstriction

Epinephrine Adverse effects

Hypertensive crisis

Dysrhythmias

Angina pectoris

Necrosis following extravasation

Hyperglycemia

Epinephrine Pharmacokinetics

significant first pass effect so must be given parenterally; short half-life may require follow-up treatment

Epinephrine drug interactions

MAO inhibitors

TCAs

General Anesthetics

Alpha and Beta Blockers

Norepinephrine

adrenergic agonist; Stimulates all receptors EXCEPT Beta-2 (no bronchodilation or hyperglycemia)

Norepinephrine indications

Hypotension

Dopamine

Catecholamine and precursor to NE; stimulates beta-1 and alpha-1 receptors

Dopamine indication

vasopressor used in treating shock

Dopamine administration

IV administration only in acute care setting; weight based dosing

Noncatecholamine Adrenergic Agonists

Nonpolar; slowly metabolized by MAO; longer half-life; given PO

Albuterol

Selective Beta-2 agonist; bronchodilator used for asthma

Phenylephrine

alpha-1 agonist; potent vasoconstrictor

Phenylephrine Indications

hypotension, shock, nasal decongestant, pupil dilation