Andrenergic Agents Flashcards
Adrenergic agents
Drugs that stimulate the sympathetic nervous system (sns)
Aka adrenergic agonists and sympathomimetics
Characteristics of adrenergic agents
Mimic the effects of the SNS transmitters norepinephrine and epinephrine
Adrenergic receptors
Located throughout the body
Are receptors for the sympathetic neurotransmitters
Alpha adrenergic
Beta adrenergic
Dopaminergic receptors: respond to dopamine
cardiovascular: blood vessels
alpha 1 receptors: constriction
beta 2 receptor: dilation
cardiovascular: cardiac muscle
beta 1: increased contractility
cardiovascular: atrioventricular node
beta 1: increased heart rate
cardiovascular:
sinoartial node
beta 1: increased heart rate
endocrine: pancrease
beta 1: decreased insulin release
endocrine: liver
beta 2: glycogenolysis
endocrine: kidney
beta 2: increased renin secretion
gastrointestinal: muscle
beta 2: decreased motility
gastrointestinal: sphincters
Alpha 1: constriction
genitourinary: bladder sphincter
alpha 1: constriction
genitourinary: penis
alpha 1: ejaculation
genitourinary: uterus
alpha 1: contraction
beta 2: relaxation
respiratory: bronchial muscles
beta 2: dilation
ocular: pupilary muscles of the iris
alpha 1: mydriasis
alpha- adrenergic receptors
divided into alpha 1 and alpha 2 receptors
differentiated by their location on nerves
alpha 1- adrenergic receptors
located on the postsynaptic effector cells (the cell, muscle or organ that the nerve stimulates)
alpha 2 adrenergic receptors
located on the presynaptic nerve terminals (the nerve that stimulates the effector cells)
controls the release of neurotransmitters
found in the CNS
predominant alpha- adrenergic agonist responses
vasocontriction and CNS stimulation
beta- adrenergic receptors
all are located on the post synaptic effector cells
beta 1 adrenergic receptors are located primarily on the heart
beta 2 adrenergic receptors- located primarily in the lungs
beta adrenergic agonist response
bronchial, GI, and uterine smooth muscle relaxation, cardiac stimulation (increased heart rate and contractility.)
dopaminergic receptors
additional adrenergic receptor
stimulated by dopamine
causes dilation of the renal vessel, the mesentaric vessels, coronary vessels, and cerebral vessel and results in INCREASED blood flow
Mechanism of action:
direct acting sympathomimetic
binds directly to the receptor and causes a physiologic responses
example: epinephrine
mechanism of action:
indirect acting sympathomimetic
causes release of catecholamines (neurotransmitters) from storage sites in the nerve endings
the catecholamine then binds to the receptors and causes a physiologic response
example: amphetamines
mechanism of action: mixed acting sympathomimetic
directly stimulates the receptor by binding to it and
indirectly stimulates the receptor by causing the release of stored neurotransmitters from the vesicles in the nerve endings.
example: ephedrine
catecholamines
substances that can produce a sympathomimetic response
endogenous: the body produces it (epinephrine, norepinephrine, and dopamine)
synthetic: everything else and endogenous
Drug effects:
stimulation of beta 1 adrenergic receptors on the myocardium, AV node, and SA node results in cardiac stimulation
increased force of contraction (positive inotropic effect)
increased heart rate
(positive chronotropic effect)
increased conduction through the AV node (positive dromotropic effect)
Beta 2 agonists- inhalers
mechanism of Action (MOA)
- stimulates beta adrenergic receptors and exhibits a response.
- indications: bronchodilator to treat asthma or COPD
examples: albuterol, terbutaline, levalbuterol
albuterol (most widly used inhaler)
brand names: ProAir, Proventil, Ventolin
available as both an inhaler solution and inhaler
dose: 1-2 inhalations every 4-6 hours as needed for condition (wheezing, shortness of breath)
also used as an inhalation liquid for breathing machine
- 2.5mg in 3mL normal saline inhalation via breathing machine every 4-6 hours
Levalubuterol (inhaler that isn’t as widely used)
advantages: less tachycardia (not widely proven)
brand names: xopenex (both inhalation liquid and inhaler)
dose: 0.63 - 1.25mg inhalation every 8 hours as needed
1-2 puffs inhalation every 4-6 hours.
terbutaline (not used as much, mainly in childbirth if it is used at all)
brand name: brethine
additional use: tocolytic agent (stops contractions)
dose: asthma/ COPD 0.25mg subcutaneous, may repeat in 15-30 minutes (maximum 0.5 in 4 hour period)
tocolytic: 2.5-10mcg/minute
Beta-Adrenergic side effects
CNS: Mild tremors, headache, nervousness, dizziness
Cardiovascular: increased heart rate, palpitations (dysrhythmias), fluctuations in blood pressure
other: sweating, nausea, vomiting, muscle cramps
vasoactive sympathomimetics (pressors, inotropes)
also called cardioselective sympathomimetics
used to support the heart during cardiac failure or shock. various alpha and beta receptors are affected
NOTE: these agents need intensive monitoring and MUST be placed on an IV pump. Many are weight based calculated and DILUTED prior to use. know your institutions guidelines
what does dobutamine stimulate?
Beta 1 receptors
what does ephedrine stimulate
alpha 1 and beta 1 receptors
what does phenylephrine stimulate?
alpha 1 receptors
what does dopamine stimulate?
alpha 1, beta 1 and dopaminergic receptors
what does epinephrine stimulate?
alpha 1, beta 1 and beta 2
what does isoproterenol stimulate?
beta 1 beta 2
what does norepinephrine stimulate?
alpha 1 and beta 1
epinephrine
MOA stimulates alpha 1, beta 1 and beta 2 receptors
indications: anaphylactic reactions, cardiac arrest, bronchodilator to treat asthma or COPD
dose: anaphylaxis 0.3 mg IM, SQ every 20 mins for 3 doses
Cardiac arrest 1mg IV every 3-5 mins until return of spontaneous circulation
hypotension/shock 0.02mcg/kg/min
CONTINUOUS INFUSION MUST BE MIXED AND DILUTED
extravasation
the vein breaks with the IV in it
epinephrine monitoring
pulmonary function, heart rate, blood pressure, extravasation
dopamine MOA
stimulates dopamine, alpha 1 and beta 1 receptors (dose dependent)
indications for dopamine
shock; increase renal perfusion
what receptors does dopamine stimulate?
renal receptors, alpha, beta
dopamine doses:
low
intermediate and high
low: 1-3 mcg/kg/min (stimulates renal receptors)
intermediate: 3-10 mcg/kg/min
(stimulates beta receptors)
high: >10mcg/kg/min (stimulates alpha receptors)
dopamine monitoring
blood pressure, ECG, heart rate, MAP (mean arterial pressure) & renal output.
dobutamine MOA
stimulates beta 1 adrenergic receptors, causing increased contractility and heart rate with little effect on beta 2 receptors
indications for dobutamine
short- term management of patients with cardiac decompensation
dobutamine dose
2.5-20 mcg/kg/minute
monitoring dobutamine
blood pressure, ECG, heart rate, MAP, urine output
phenylephrine MOA
direct acting alpha 1 stimulater. must be diluted prior to administration
indications of phenylephrine
treatment of hypotension, vascular failure in shock; vasoconstrictor in regional analgesia.
phenylephrine dose:
0.25 mcg/kg/min
monitoring phenylephrine
blood pressure; heart rate
norepinephrine MOA
stimulates beta 1 and alpha 1 receptors (presser)
MUST BE DILUTED
indications of norepinephrine
treatment of shock
norepinephrine dose:
0.02-0.5mcg/kg/minute
monitoring norepinephrine:
blood pressure and heart rate
ephedrine MOA
stimulates alpha 1 and beta 1 receptors
stimulates beta adrenergic receptors and exhibits a response
indications of ephridrine
treatment of nasal congestion; hypotension
ephedrine dose
5-25mg slow IV push, may repeat after 5-10 mins as needed then every 3-4 hrs. DO NOT EXCEED 150mg/24hrs
monitoring ephedrine
blood pressure & heart rate
isoproterenol MOA
stimulates beta 1 and beta 2 receptors
MUST BE DILUTED
indications of isoproterenol
heart block, cardiac arrest, bronchospasm during anesthesia
isoproterenol dose
2-10mcg/minute
monitoring isoproterenol
ECG, heart rate & respiratory rate
alpha adrenergic side effects on the CNS
headaches, restlessness, excitement, insomnia, euphoria
alpha adrenergic side effects on the cardiovascular system
palpitations, tachycardia, vasoconstriction, hypertension
alpha adrenergic side effects (other)
anorexia, dry mouth, nausea, vomiting, taste changes
beta adrenergic side effects on the CNS
mild tremors, headache, nervousness, dizziness
beta adrenergic side effects on the cardiovascular system
increased heart rate, palpitations, fluctations in BP
beta adrenergic side effects (other)
sweating, nausea, vomiting, muscle cramps
nursing implications for intravenous administration
- check IV site often for infiltration
- use clear IV solutions
- use infusion device/IV pump
- infuse agent slowly to avoid dangerous cardiovascular effects
- monitor cardiac rhythm.