Adrenergic Drugs Flashcards
what is the major mechanism for termination of action of adrenergics?
reuptake
what are the ways that drugs affect adrenergic transmission?
norepinephrine synthesis
vesicle uptake of neurotransmitter
release of neurotransmitter
receptor interactions
reuptake
metabolism
what are the adrenergic receptors?
alpha receptors: alpha1 and alpha2
beta receptors: beta1, beta2, and beta3
dopamine receptors: D1-D5
what is the response to receptor activation of alpha1 receptors?
contraction (arteries, veins, uterus)
what is the response to receptor activation of alpha2 receptors?
inhibit norepinephrine release at presynaptic nerve endings
decrease sympathetic tone at postsynaptic in CNS
what is the response to receptor activation of beta1 receptors?
increased heart rate and force of contraction
what is the response to receptor activation of beta2 receptors?
dilation of arterioles
relaxation of bronchial and uterine smooth muscle
what is the response to receptor activation of beta3 receptors?
increased lipolysis in lipocytes
what is the response to receptor activation of D1 receptors?
dilation of arterioles of kidney and mesentery
what is essential in activation of alpha1 receptors?
calcium
what happens intracellularly after an alpha2 receptor is activated?
decrease in cAMP
what happens intracellularly after a beta receptor is activated?
increase in cAMP
how can beta2 receptors and alpha1 receptors lead to opposite actions through a similar route?
MLC is phosphorylated in alpha1, leading to smooth muscle contraction
MLC is not phosphorylated in beta2, leading to smooth muscle relaxation
what is the mechanism of action for alpha1 receptors?
increase calcium
what is the mechanism of action for alpha2 receptors?
decrease cAMP
open potassium channels
close calcium channels
what is the mechanism of action for beta1, beta2, and beta3 receptors?
increase cAMP
increased cAMP increases calcium in heart
what is the mechanism of action for D1 receptors?
increase cAMP
what is the mechanism of action for D2 receptors?
decrease cAMP
open potassium channels
decrease calcium flux
what are the systemic effects of the sympathetic nervous system? what receptors lead to what?
increased blood pressure: alpha1 and beta1
decreased blood pressure: beta2
increased kidney perfusion: D1
sedation and decreased blood pressure: alpha2
what are some direct acting adrenergic agonists?
epinephrine
norepinephrine
isoproterenol
phenylephrine
dobutamine
terbutaline
what are some indirect acting adrenergic agonists?
tyramine
phenylpropanolamine
amphetamine
what are some mixed acting adrenergic agonists?
ephedrine
dopamine
how do alpha1 adrenergic agonists affect blood pressure?
increases blood pressure
how do adrenergic agonists (mostly beta1) affect the heart?
increase force of contraction
increase rate of contraction
increase cardiac output
increase excitability
increase automaticity
decrease efficiency
how does phenylephrine (alpha1) affect heart rate and blood pressure?
increase blood pressure
compensatory bradycardia
how does epinephrine (alpha, beta1 and beta2) affect heart rate and pressure?
increase blood pressure but not as much as alpha1
increase rate
how does isoproterenol (beta1 and beta2) affect blood pressure and heart rate?
beta1 initially increases blood pressure
beta2 then drops blood pressure and raises heart rate
how do adrenergic agonists affect the gastrointestinal system?
motility decreased by alpha2 and beta2
increased sphincter contraction by alpha1
what are the metabolic effects of adrenergic agonists?
increase blood glucose by beta2
decrease insulin secretion by alpha2
stimulate glucagon secretion by beta2
high concentration: metabolic acidosis and decrease serum potassium
what are the clinical applications of adrenergic agonists?
anaphylactic shock and hypersensitivity reactions (epinephrine)
congestive heart failure (dobutamine and dopamine)
AV block
cardiac and septic shock (dopamine)
cardiac arrest (epinephrine)
local hemostatic agents (alpha1agonists)
prolong local anesthetic effects (epinephrine)
nasal decongestants (alpha1 agonists)
urinary bladder sphincter incompetence (alpha1 agonist, ephedrine, phenylephrine)
bronchodilator (terbutaline, beta2 agonists)
open-angel glaucoma (epinephrine)
reduce synechia (iris to cornea) formation (alpha1 agonist, phenylephrine)
sedation (alpha2 agonist)
what are the adverse effects of adrenergic agonists?
CNS: anxiety, fear, restlessness
cardiovascular and other: cardiac arrhythmia, tachycardia, reflex bradycardia, hypertension, tachyphylaxis, nasal irritation, local necrosis
what are the pharmacological effects of adrenergic alpha-antagonists on the cardiovascular system?
decrease blood pressure
epinephrine reversal
what are the clinical applications of adrenergic alpha-antagonists with the cardiovascular system?
hypertension, congestive heart failure
what do adrenergic beta-antagonists do to the cardiovascular system?
decrease heart rate (anti beta1)
decrease force of contraction (anti beta1)
decrease AV conduction (anti beta1)
decrease blood pressure (anti beta1 and beta2)
what do adrenergic beta-antagonists do to the respiratory system?
bronchoconstriction (anti beta2)
what do adrenergic beta-antagonists do to the eye?
reduce intra-ocular pressure (anti beta2)
what are the clinical applications of adrenergic beta-antagonists with the cardiovascular system?
cardiac arrhythmia (anti beta1)
hypertension (anti beta1)
hypertrophic cardiomyopathy in cats (anti beta1)
what are the clinical applications of adrenergic beta-antagonists with ophthalmology?
glaucoma (timolol)
what are the adverse effects of adrenergic alpha-antagonists?
hypotension (anti alpha1)
reflex tachycardia (anti alpha1)
CNS stimulation (anti alpha2)
what are the adverse effects of adrenergic beta-antagonists?
decreased cardiac output (anti beta1)
bradycardia (anti beta1)
bronchospasm (anti beta2)
what do alpha1 adrenergic agonists do to the gastrointestinal system?
increase sphincter tone
what do alpha2 and beta2 adrenergic agonists do to the gastrointestinal system?
decrease motility
