Adrenergics: Catecholamines Flashcards
Causes peripheral excitatory action on certain types of smooth muscle (blood vessels, radial
muscle) and on glands (salivary and sweat)
Catecholamines
Drug with peripheral inhibitor action on certain types of smooth muscle (wall of gut, bronchial
tree, blood vessels supplying skeletal muscle)
Catecholamines
Causes cardiac excitatory action that increases heart rate and force of contraction
Catecholamines
Catecholamine has metabolic actions: ______ glycogenolysis (liver and muscle) and liberation of ________
Increase
FFAs
Catecholamine’s action: endocrine actions: modulate the secretion of ______ and ______
insulin DECREASE
renin INCREASE
Catecholamine actions in the CNS: respiratory ______, _______ in wakefulness and
psychomotor activity, _______ in appetite
stimulation
increase
reduction
Catecholamines have prejunctional actions that either inhibit or facilitate the release of neurotransmitters, the _____ action being most important
inhibitor
Catecholamines and adrenergic agonists are
sympathomimetics
drugs mimic the effects of transmitter substances of the sympathetic nervous system
Sympathomimetic
How do sympathomimetic drugs work?
These drugs act at the postganglionic sympathetic terminal,[1] either directly activating postsynaptic receptors, blocking breakdown and reuptake, or stimulating production and release of catecholamines.
Adrenergic antagonists are an example of
(sympatholytics)
Adrenergic antagonists: most are _______ antagonists (exception is phenoxybenzamine)
competitive
How is it possible for adrenergic anatagonists to interfere selectively with responses that result from sympathetic stimulation
compounds have been developed with different affinities for the various receptors
Adrenergic receptor subtype:
α1 located in the Eye does
Contraction of the radial muscle of the iris (mydriasis)
Adrenergic receptor subtype:
α1 located in the arteries and veins does
constriction
Adrenergic receptor subtype:
α1 located in the GU smooth muscle for male does
constriction
Adrenergic receptor subtype:
α2 located in Pre-synaptic nerve
causes Inhibition of transmitter release terminals
Adrenergic receptor subtype:
α2 located in CNS causes
Inhibition of sympathetic outflow
Adrenergic receptor subtype:
β1 located in Heart causes
Increased rate and force of contraction &
Increased A-V conduction velocity
Adrenergic receptor subtype:
β1 located in Kidney causes
Renin release
Adrenergic receptor subtype:
β2 located in Arteries (skeletal muscle)
Dialation
Adrenergic receptor subtype:
β2 located in Bronchi
Dialation
Adrenergic receptor subtype:
β2 located in skeletal muscle
Glycogenolysis
Adrenergic receptor subtype:
β2 located in liver
Glycogenolysis, gluconeogenesis
Adrenergic receptor subtype: Dopamine1
located in the Kidney causes
Dilation of kidney vasculature
Adrenergic Agonists:
Substitution of OH groups at the __ and __ position of aromatic ring is necessary for maximal α and β activity
3 and 4
Adrenergic Agonists:
Presence of 2 carbon atoms between ______ and ______the affords the greatest sympathomimetic activity.
aromatic ring and amino group
Adrenergic Agonists:
Substitution of alkyl groups on the amino group tend to ↑ ______ (i.e., isoproterenol).
β activity
Adrenergic Agonists:
phenylephrine is an
α1 agonist
Adrenergic Agonists:
What increases the oral effectiveness and duration of action of many compounds especially those with an α-CH3 group (i.e. amphetamine)
Absence of one or both OH groups (especially the 3-OH)
Adrenergic Agonists:
What makes the compound more resistant to MAO (i.e., amphetamine).
Substitution on the α carbon
Adrenergic Agonist Substitution of OH on β-carbon will cause what changes: lipid solubility CNS action peripheral alph and beta activity
↓ lipid solubility
↓ CNS action but
↑ peripheral α and β activity.
Norepinephrine (Levophed®) is what type of NT
- sympathetic neurotransmitter
Norepinephrine Receptor selectivity for
α1, α2, β1
Nepi has CV effect through which receptor?
Cardiovascular effects - α1 mainly
Nepi causes peripheral _______ which results in ______ peripheral vascular resistance
vasoconstiction
increased
Nepi will ______ BP and cause reflex ______
increase BP
reflex bradycardia
In IC situations, you could use Nepi as:
used as a vasoconstrictor under certain intensive care situations (i.e., shock)
If you have reduced sympathetic tone d/t neurological injury or during use of spinal anesthesia, Nepi could be used to…
elevate BP
Epinephrine is naturally occurring, synthesized in ?
adrenal medulla
What receptors is epinephrine selective for?
Receptor selectivity - α1, α2, β1, β2
Epinephrine CV effects:
_____heart rate, contractile force, cardiac output
increase
Epinephrine CV effects:
________ systolic, _______ diastolic blood pressure
increase/decrease
CV effects of Epi:(dose-dependent)
Causes ______of most vascular beds and ______of skeletal muscle blood vessels (dose-dependent
constriction
dialation
Nepi has a net effect to ______ peripheral vascular resistance
decrease
In the Respiratory system Epi causes
Bronchodilation
Epi causes Hyperglycemia by:
stimulating gluconeogenesis and glycogenolysis; inhibits insulin release
Epi causes Lipolysis in order to:
increase free fatty acids
Therapeutic use of ______ for
Rapid relief of hypersensitivity reactions to drugs and other allergens
Therapeutic uses of Epi
This drug is Co-administered with local anesthetics to increase duration of action
Epinephrine
In pts w/ Bradyarrhythmias, Epi can be used to
– restore rhythm in patients with cardiac arrest
What are some ophthalmic uses for Epi
mydriatic, decrease hemorrhage, conjunctival decongestion
Isoproterenol (Isuprel®)
Receptor selectivity
β1, β2
Cardiovascular effects of Isoproterenol
_______ peripheral resistance
Decrease
Cardiovascular effects of Isoproterenol
________heart rate, contractile force, CO
increase
Cardiovascular effects of Isoproterenol
_____ mean blood pressure
Decrease
Respiratory effects of Isoproterenol
Bronchodialation
In emergencies use this drug to stimulate heart rate during bradycardia or heart block
Isoproterenol
Dopamine (Intropin®) synthesis is:
- naturally occurring NT
Receptor selectivity of dopamine
- DA1, β1, α1
Cardiovascular effects of Dopamine
Low dose causes______ of renal and mesenteric arteries
vasodilation
Cardiovascular effects of Dopamine
Low dose causes ________ peripheral resistance through this receptor
decrease via DA1 receptor
CV effects of Dopamine: medium dose
_______ heart rate, contractile force, cardiac output via ______
Increase
β1
CV effects of dopamine: high dose
vasoconstriction/vasodialation and ______ peripheral resistance (α1)
vasoconcstriction
increase
(α1)
When you have severe decompensated heart failure, shock (cardiogenic; septic) what drug would you use?
Dopamine
Dobutamine (Dobutrex®) is a
- synthetic catecholamine
Receptor selectivity for dobutamine
- (-) dobutamine
– α1 agonist & β agonist
Receptor selectivity for dobutamine
- (+) dobutamine
– α1 antagonist & β agonist
What is the overal effect of a racemic mixture of dobutamine?
β1 agonist
Cardiovascular effects of Dobutamine
_____ cardiac rate, contractility and output
Increased
CV effects of Dobutamine:
Minimal change in
peripheral resist & blood pressure
What drug would you prescribe for short-term treatment of cardiac decompensation (surgery, CHF, MI)
Dobutamine
What drug is used for cardiac stress testing
Dobutamine
Methyldopa (Aldomet®) is metabolized in
adrenergic nerve terminals in CNS
What is Methyldopa broken down into?
α-methyldopamine and α-methylnorepinephrine, which are stored in nerve terminals and released with stimulation
What is the significance of α-methyldopamine and α-methylnorepinephrine in regards to α2 receptor and central α2 receptors
potent α2 receptor agonists; stimulate central α2 receptors to reduce sympathetic outflow
CV action of methyldopa:
_____ peripheral resistance, heart rate, and cardiac output
Decrease
Major therapeutic use of Methyldopa?
anti-hypertensive
What side effects would one experience with sudden discontinuance of Methyldopa?
sedation, dry mouth, edema, rebound hypertension
