Chapter 13 Autonomic & Cardiac Pharmacology Flashcards
naturally occurring catecholamines
epinephrine, norepinephrine, dopamine
synthetic catecholamines
ephedrine, phenylephrine, dobutamine
use these drugs in a variety of situations like
- anesthesia-induced hypotension
- bradycardia
- anaphylaxis
- heart failure
- cardiac resucitation
inotropic
force of contraction
chronotropic
heart rate
dromotropic
conduction velocity
beneficial effects of beta stimulation
- bronchodilation
- vasodilation
- stabilization of mast cells –> decrease in histamine release
beneficial effects of alpha stimulation
decrease in bronchial secretion
net effect is a decrease in airway resistance with an improvement on oxygenation
low dose epi is how much and what does it do?
- 10mcg/min
- peripheral vasculature promotes the redistribution of blood flow to skeletal muscle producing a decrease in SVR
what happens as the dose of epi increases?
the alpha effect predominates resulting in vasoconstriction and an increase in SVR
SBP increases while DBP remains unchanged –> increase in PP
increased alpha effect that occurs with epi also results in
renal and splanchnic vasoconstriction
renal blood flow decreases
MECHANISM 1
interference with synthesis of transmitter: cholinergic system
- choline acetyltransferase inhibitors
- minimal depletion of Ach
- sympatholytic
MECHANISM 1
interference with synthesis of transmitter: adrenergic system
- ⍺- methyl tyrosine (inhibition of tyrosine hydroxylase)
- depletion of NE
- sympatholytic
MECHANISM 2
metabolic transformation by same pathway as precursor of transmitter : adrenergic
- methyldopa
- displacement of NE by ⍺- methyl- NE, which is an ⍺2 agonist, like clonidine, that reduces sympathetic outflow
- sympatholytic
MECHANISM 3
blockade of transport system at nerve terminal membrane: cholinergic
- hemicholinium
- block of choline uptake with consequent depletion of ACh
- sympathomimetic
MECHANISM 3
blockade of transport system at nerve terminal membrane: adrenergic
- cocaine, imipramine
- accumulation of NE at receptors
- sympathomimetic
MECHANISM 4
blockade of transport system at nerve terminal membrane: cholinergic
- vesamicol
- block of ACh storage
- sympatholytic
MECHANISM 4
blockade of transport system at nerve terminal membrane: adrenergic
- reserpine
- destruction of NE by mitochondrial MAO, and depletion of adrenergic terminals
- sympatholytic
MECHANISM 5
promotion of exocytosis or displacement of transmitter from axon terminal: cholinergic
- latrotoxins
- cholinomimetic followed by anticholinergic
- sympathomimetic
MECHANISM 5
promotion of exocytosis or displacement of transmitter from axon terminal: adrenergic
- amphetamine, tyramine
- adrenomimetic
- sympathomimetic
MECHANISM 6
prevention or release of transmitter: cholinergic
- botulinum toxin
- anticholinergic
- sympatholytic
MECHANISM 6
prevention or release of transmitter: adrenergic
- clonidine, dexmedetomidine
- antiadrenergic
- sympatholytic
MECHANISM 7
mimicry of transmitter at postjunctional sites: cholinergic
- Muscarinic –> cholinomimetic –> sympathomimetic
- nicotinic –> methacholine/bethanachol –> cholinomimetic –> sympathomimetic
MECHANISM 7
mimicry of transmitter at postjunctional sites: adrenergic
⍺1:
- nicotine/epibatidine
- selective alpha-1 adrenomimetic
- sympathomimetic
⍺2:
- phenylephrine
- adrenomimetic (periphery)
- sympathomimetic
⍺1, ⍺2:
- oxymetazoline
- nonselective adrenomimetic
- sympathomimetic
β1:
- dobutamine
- selective cardiac stimulation
- sympathomimetic
β2:
- terbutaline, albuterol
- selective β2 receptor agonist (selective inhibition of smooth muscle contraction)
- sympathomimetic
β1, β2:
- isoprotenerol
- nonselective β adrenomimetic
- sympathomimetic
MECHANISM 8
blockade of postsynaptic receptors: cholienrgic
- muscarinic –> atropine, muscarinic blockade, sympatholytic
- nicotinic –> d-tubucuraine/atracurium, neuromuscular blockade, sympatholytic
- nicotinic –> trimethaphan, ganglionic blockade, sympatholytic
MECHANISM 8
blockade of postsynaptic receptors: adrenergic
⍺1, ⍺2: phenoxybenzamine, nonselective ⍺ blockade (irreversible) –> sympatholytic
⍺1, ⍺2: phentolamine, nonselective ⍺ blockade (reversible) –> sympatholytic
⍺1: prazosin/terazosin/doxazosin, selective alpha1 receptor blockade (reversible) –> sympatholytic
⍺2: yohimbine, selective alpha2 receptor blockade –> sympatholytic
β1, β2: propanolol, nonselective beta-receptor blockade –> sympatholytic
β1: metoprolol/atenolol, selective beta 1 recepetor blockade –> sympatholytic
MECHANISM 9
inhibition of enzymatic breakdown of transmitter: cholinergic
AChE inhibitors (edrophonium/neostigmine) –> cholinomimetic (muscarinic sites) depolarization blockade (nicotinic sites) –> parasympathomimetic
MECHANISM 9
inhibition of enzymatic breakdown of transmitter: adrenergic
nonselective MAO inhibitors (pargyline/nialamide), little direct effect on NE or sympathetic response; potentiation of tyramine –> parasympathomimetic
selective MAO-B inhibitor (selegiline), adjunct in Parkinson’s dx –> parasympathomimetic
peripheral COMT inhibitor (entacapone), adjunct in Parkinson’s dx –> parasympathomimetic
peripheral and central COMT inhibitor (tolcapone), adjunct in Parkinson’s dx –> parasympathomimetic
MECHANISM 10
interference with the second messenger system: adrenergic
PDE 3 inhibitors (milrinone), inotrope –> sympathomimetic
the conversion of tyrosine to __ by __ __ is inhibited by increased NE synthesis
DOPA; tyrosine hydroxylase
where is epinephrine synthesized?
adrenal medulla
sympathetic effect of:
radial muscle, iris
contraction (mydriasis), alpha 1
parasympathetic effect of:
sphincter muscle, iris
contraction (miosis) M3,M2
