Lecture 7 - autonomic pharmacology 1 Flashcards
what does cAMP inhibit
myosin light chain kinase
what are the anatomic locations of alpha-1 receptors
- vascular smooth muscle
- iris
- urinary tract sphincters
- GI smooth muscle
- CNS
what are the anatomic locations of alpha-2 receptors
- blood vessels
- glands
- GI tract
- eyes/CNS
- platelets
describe the properties of alpha-adrenergic agonists. give examples
- naturally occurring and synthetic
- evoke responses of the SNS
ex: epinephrine, norepinephrine, phenylephrine, ephedrine
T/F: the selectivity of a drug can be dose-dependent
TRUE
what are the 4 general uses of alpha-1 agonists
- vasoconstriction
- treat anaphylaxis
- manage urinary incontinence
- mydriasis
classify epinephrine
selective or non-selective?
common uses?
routes of administration?
- non-selective (all alpha and beta receptors)
- CPR, anaphylactic shock, local anesthetics
- IV, interosseous, intratracheal, topical
a high dose of epinephrine will cause
vasoconstriction at A1
T/F: epinephrine is the preferred drug to use as a local anesthetic for tail or digit amputations due to its vasoconstriction properties
FALSE - can cause tissue necrosis
a low dose of epinephrine will cause
vasodilation at B2
what cardiac effects can be seen by epinephrine usage
increased heart rate and force of contraction
may result in VPCs or V-fib
classify norepinephrine
selective or non-selective?
common uses?
routes of administration?
- selective for alpha effects (will bind B1)
- manage hypotension under anesthesia
- IV, infusion
do we need to give a loading dose of norepinephrine? why?
No - short half-life will reach a steady state quickly
classify dopamine
selective or non-selective?
common uses?
routes of administration?
- dose-dependent selectivity
- hypotension under anesthesia
- infusion
T/F: dopamine formulations are made to last long periods
FALSE - has a short half-life and formulations do not have preservatives
what is the most selective alpha-1 agonist
phenylephrine
classify phenylephrine
selective or non-selective?
common uses?
routes of administration?
- most selective
- increase BP, nasal edema tx, nephrosplenic entrapment (vasoconstriction)
- topical, infusion
what are the s4 ide effects of phenylephrine
- tissue/organ damage from decreased blood flow
- hypertension
- reflex bradycardia
- arrhythmias
at low doses, dopamine binds _____ receptors
dopaminergic
at medium doses, dopamine binds ____ receptors
beta
at high doses, dopamine binds ____ receptors
alpha
what alpha agonist crosses the blood-brain barrier
ephedrine
classify ephedrine
selective or non-selective?
common uses?
routes of administration?
- mixed (direct and indirect)
- maintain BP, decongestant, bronchodilation
- oral
what are the direct effects of ephedrine
a1 and beta receptor binding
what are the indirect effects of ephedrine
increase NE release
what are the side effects of ephedrine use
- hypertension
- arrhythmias
- urinary sphincter contraction
- CNS stimulation
define sympatholytic
blocks actions of the sympathetic nervous system
what are alpha-1 antagonist drugs?
- phenoxybenzamine
- prazosin
T/F: phenoxybenzamine binds irreversibly to receptors
TRUE
classify phenoxybenzamine
selective or non-selective?
common uses?
routes of administration?
- non-specific
- hypertension, urinary retention
- oral (needs compounding)
pheochromocytoma
malignant, functional adrenal tumor that increases epi/norepi
under what conditions will phenoxybenzamine be avoided
if the patient is at risk for hypotension, going into systemic shock, or CHF
chronic use may be avoided with patients with preexisting kidney disease
T/F: phenoxybenzamine can cause hypotension and reflex tachycardia under anesthesia
TRUE
classify prazosin
selective or non-selective?
common uses?
routes of administration?
- more selective for A1
- oral
- vasodilation (uncontrolled hypertension), smooth muscle relaxation
what organs will be affected in uncontrolled hypertension
- brain
- kidneys
- eyes
- heart
what precautions should be taken with prazosin use
- caution with chronic renal failure (hypotension will decrease flow to kidneys)
- bradycardia possible due to decreased sympathetic outflow
- CNS effects
what drug blocks NE uptake and storage to “calm” equine patients
reserpine
