Adrenergic 1 Flashcards
MIXED-ACTING ADRENERGIC AGONISTS?
EPHEDRINE
PSEUDOEPHEDRINE
• Induce release of norepinephrine
• Activate adrenergic receptors.
Ephedrine structure, pk, and uses
• Not a catecholamine: poor substrate for COMT
and MAO. Long duration of action.
• Excellent absorption orally and penetrates the
CNS.
EPHEDRINE: USES
• Used as a pressor agent, particularly during
spinal anesthesia.
• Used in myasthenia gravis.
PSEUDOEPHEDRINE uses?
• One of four ephedrine enantiomers.
• Available over the counter as a component of
many decongestant mixtures.
UPTAKE INHIBITORS?
COCAINE
ATOMOXETINE
MODAFINIL
MODAFINIL use?
• Psychostimulant. • MOA not fully known. • Inhibits norepinephrine and dopamine transporters. • Increases synaptic concentrations of norepinephrine, dopamine, serotonin and glutamate, and decreases GABA levels. • Used for the treatment of narcolepsy.
ATOMOXETINE use?
• Selective inhibitor of the norepinephrine
reuptake transporter.
• Indicated for the treatment of ADHD.
Cocaine use?
• Blocks monoamine reuptake.
• Monoamines accumulate in synaptic space.
• This results in potentiation and prolongation of
their central and peripheral actions.
RELEASING AGENTS?
AMPHETAMINE
METHYLPHENYDATE
TYRAMINE
• Cause norepinephrine release from presynaptic
terminals.
• Potentiate effects of norepinephrine produced
endogenously.
AMPHETAMINE use?
• Has central stimulatory action.
• Can increase blood pressure by alpha-agonist action
on vasculature as well as beta-stimulatory effects
on heart.
USES
• ADHD
• Narcolepsy
METHYLPHENIDATE use?
- Structural analogue of amphetamine.
* Used to treat ADHD in children.
Tyramine consequence?
• Found in fermented foods such as ripe cheese and Chianti wine. • Normally oxidized by MAO. • If the patient is taking MAO inhibitors, it can precipitate serious vasopressor episodes.
BRIMONIDINE use?
• Highly selective alpha-2 agonist. • Given ocularly to lower intraocular pressure in glaucoma. • Reduces aqueous humor production and increases outflow.
Methyldopa use and moa?
• Taken up by noradrenergic neurons.
• Converted to alpha-methylnorepinephrine which
activates central alpha2-adrenoceptors.
• This decreases blood pressure.
• Drug of choice for treatment of hypertension
during pregnancy.
• Adverse effects: sedation, impaired mental
concentration, xerostomia.
Clonidine use?
• Partial alpha2 agonist.
• Centrally acting antihypertensive.
• Activates central presynaptic alpha2-adrenoceptors.
• Reduces sympathetic outflow. This reduces
blood pressure.
• Adverse effects: lethargy, sedation, xerostomia.
PHENYLEPHRINE actions?
alpha 1-SELECTIVE ADRENERGIC AGONISTS
• Vasoconstriction: alpha 1 effect.
• Nasal decongestant . Given orally or topically.
• Mydriatic.
• Used to increase blood pressure in hypotension resulting from vasodilation in septic shock or
anesthesia.
• Used to increase blood pressure and terminate episodes of supraventricular tachycardia.
Beta2-ADRENERGIC AGONISTS
- Evoke bronchodilation (beta2 effect)
* Used in asthma.
Albuterol use?
SHORT-ACTING
• For management of acute asthma symptoms.
Salmeterol & formoterol
LONG-ACTING
• Prolonged duration of action: 12 hours.
• Slow onset of action: not for prompt relief of acute
symptoms.
DOBUTAMINE action and uses?
beta 1-SELECTIVE ADRENERGIC AGONISTS
• Predominantly a beta1 agonist.
• Potent inotrope, with comparatively mild chronotropic effects.
• Produces less increase in HR and less decrease in PVR than isoproterenol.
• Causes mild vasodilation.
• Increases myocardial O2 consumption. This is the basis of the dobutamine stress echocardiogram.
DOBUTAMINE: USES
• Management of acute heart failure.
• Management of cardiogenic shock.
Isoproterenol uses, moa, effects?
• Activates beta 1 and beta 2 adrenergic receptors
• Increases heart rate, force of contraction, and
cardiac output (beta 1 effect).
• Dilates arterioles of skeletal muscle (beta 2 effect),
resulting in a decrease in peripheral vascular
resistance.
• Diastolic pressure falls. Systolic blood pressure
may remain unchanged or rise.
• Mean arterial pressure typically falls.
• Causes bronchodilation (beta 2 effect).
Isoproterenol use
• Isoproterenol may be used in emergencies to
stimulate heart rate in patients with bradycardia
or heart block
Dopamine, what receptors does it act?
• Can activate dopamine, beta and alpha receptors.
• D1 > beta 1 > alpha 1
• The cardiovascular response to dopamine
depends on the dose infused.
Low rates of dopamine infusion?
• Dopamine activates D1 receptors, in renal and other vascular beds, leading to: • Vasodilation • Increase in GFR • Increase in renal blood flow • Increase in sodium excretion
Intermediate rates of dopamine infusion?
• Dopamine activates β1 receptors in the heart,
increasing cardiac output.
• There is negligible activation of β2 receptors.
• Dopamine causes release of NE from nerve
terminals, which contributes to its cardiac effects.
• Dopamine increases SBP.
• DBP is usually not changed significantly.
• MAP is increased.
• PVR is unchanged.
High rates of dopamine infusion?
• Dopamine activates vascular alpha 1 receptors,
leading to vasoconstriction and a rise in
blood pressure.
• Total peripheral resistance may be increased
Dopamine uses?
• Used in the treatment of severe CHF.
• Used in the treatment of cardiogenic and septic
shock.
• For management of shock intermediate to
high rates of infusion are used.
Norepinephrine uses receptors act?
- Agonist at alpha 1, alpha 2, and beta 1 receptors
* Little action on beta 2 receptors
Norepinephrine effects? uses?
• Causes peripheral vasoconstriction (alpha 1 effect).
• Increases cardiac contractility (β1 effect).
• Increases peripheral vascular resistance, systolic
blood pressure and diastolic blood pressure.
• Cardiac output is unchanged or decreased.
• The increase in blood pressure triggers a
baroreceptor reflex resulting in bradycardia.
Norepinephrine uses?
• To treat shock because it increases vascular
resistance and therefore increases blood
pressure.
EPINEPHRINE: USES?
• Anaphylactic Shock: drug of choice.
• Acute asthmatic attacks.
• Cardiac arrest
• In Local Anesthetics: Epinephrine increases
duration of local anesthesia by producing
vasoconstriction at the site of injection.
When a low dose is given IV epinephrine actions?
• Peripheral resistance decreases, because beta 2
receptors are more sensitive to epinephrine
than alpha 1 receptors. Diastolic pressure falls.
• Systolic pressure increases due to increased
cardiac contractile force (beta 1 effect).
• Heart rate increases (beta 1 effect).
• There is no increase in mean blood pressure,
so the baroreceptor reflex does not kick in.
• Therefore, the effects of epinephrine depend on
the dose and the resultant ratio of the alpha 1 to beta 2
responses in the various vascular beds.
When a large dose is given IV epinephrine actions?
• There is increase in blood pressure. Due to:
1. Increased ventricular contraction (beta 1 effect).
2. Increased heart rate (beta 1 effect) This may be
opposed by the baroreceptor reflex.
3. Vasoconstriction (alpha 1 effect).
Describe epinephrine?
• Epinephrine acts as a hormone: after release
from the adrenal medulla into the blood it acts
on distant cells.
• Epinephrine is an agonist at both alpha and beta
adrenoceptors.
• At low concentrations epinephrine activates
mainly beta 1 and beta 2 receptors.
• At higher concentrations 1 effects become
more pronounced.
Epinephrine effects?
• Increases heart rate and contractile force (beta 1 effect).
• Cardiac output increases: oxygen demand of the
myocardium increases.
• Increases renin release (beta 1 effect).
• Constricts arterioles in skin and viscera (alpha 1 effect).
• Dilates blood vessels of skeletal muscle (beta 2 effect).
• Relaxes bronchial smooth muscle (beta 2 effect).
• Increases liver glycogenolysis (beta 2 effect).
• Increases glucagon release (beta 2 effect).
• Increases lipolysis (beta 1 and beta 2 effect).
