sympathomimetics Flashcards
α adrenoreceptors have greater affinity for synthetic or natural catecholamines
natural
α1 higher affinity for phenylephrine or clonidine
phenylephrine(Clonidine selectively binds to α2 rec)
α1 is which g linked receptor
Gq
α2 is which g linked receptor
Gi
what is the location of α1 and α2 receptors?
α1 — post synaptic memberane of effector organs V.C (skin & abdominal viscera
α2 on presynaptic memberane and also on b cells of pancreas
functions of α1
vasoconstriction
mydriasis
urinary retention
glycogenolysis
Dec renin release
functions of α2
feedback inhibition of N.E release
insulin release reduction
β receptor — affinity for natural or synthetic catecholamines
synthetic
β1 — affinity for epi and N.E
Equal
β2 — affinity for epi and N.E
more for epi
action of β1
ACTION ON HEART
HR inc
Contractility inc
AV conduction inc
ACTION ON KIDNEY
Renin Inc
BP inc
β2 action
bronchodilation
Skeletal vasculature bed– vasodilation– p.r dec
insulin inc
gi motility dec
inhibition of labor
CNS penetration of Catecholamines
poor
why are catechlamines rapidly deactivated
rapid metabolization by COMT
Non Catecholamines: Amphetamine. Long duration →why?
Aren’t inactivated by COMT.
b) Poor substrates for MAO.
2. High CNS penetration.
what is the effect of epi on systolic BP
INCREASES
due to action on alpha 1 and Beta 1 receptors
what is the effect of epi on diastolic BP
DEC
dueto action on beta 2 receptor
therapeutic use of epi
anaphylaxis
small amount with local anesthetic to inc duration of anesthesia(vasoconstriction)
why epinephrine isn’t used in a pt with hyperthyroidism
Due to ↑ adrenergic receptors on vasculature of hyperthyroid individual.
interaction with cocaine
cocaine inhibits reuptake of catecholamines by adrenergic neuron→ Exaggerated C.V. action.
which receptors does nor epi acts on
alpha 1 , alpha 2
beta 1
cvs effect of n.e
α1: V.C→ ↑ Systolic & diastolic B.P→ baroreceptors→ ↑vagal activity→ reflex bradycardia (but with no effect on + ve inotropic effect).
which drug blocks the vagal stimulation effect of n.e
atropine
therapeutic use of n.e
cardiogenic shock
use of isoproternol
atrioventricular block, cardiac arrest
action on receptors of isoproterenol
beta 1, beta 2
which drug is prefered for cardiogenic shock
dopamine or nor epi
dopamine
Preferred over N.E→ Why?
because N.E ↓ blood flow to kidney→ renal shut down
what is the action of dopamine on the receptor that it acts(beta 1, alpha 1, dopaminergic receptors)
Low dose→ β1→:+ve inotropic & chronotropic.
*High dose→ α1→ V.C →↑ B.P
*D2 & D1→ V.D→ ↑ blood flow to kidney
therapeutic use of dobutamine
CHF
which drug ↑ C.O with little change on cardiac rate
dobutamine
which receptor does dobutamine acts on
beta 1
therapeutic use of oxymetazoline
nasal decongestant(locally)
side effect of oxymetazoline
rebound congestion
which adrenergic agonist is used in treatment of supraventicular tachycardia
methoxamine
which adrenergic agonist is used in overcoming hypotension during surgery involving halothane
methocamine
which is the only adrenergic drug that doesn’t trigger cardiac arrhythmia which is sensitized by these general anesthetics
methoxamine
which receptors does methoxamine acts on
α1
( α1 > α2)
therapeutic use of amphetamines
adhd, narcolepsy, appetite control
moa of amphetamine
non vesicular release of catecholamines is enhanced by amphetamine
drugs in indirect acting adrenergic agonist
amphetamine
cocaine
tyramine
drugs in mixed adrenergic agonist
ephedrine
pseudoephedrine
