Adrenergic Agonists & Receptors Flashcards
Adrenergic receptors are:
Alpha 1, alpha 2, beta 1, beta 2, beta 3, D1 and D2
Directly acting adrenergic agonists are divided into:
Non-selective and selective
Directly acting adrenergic agonists which are non selective includes:
Adrenaline
Noradrenaline
Dopamine
Isoproterenol
Adrenaline acts on
Alpha 1 & 2, beta 1 & 2
When adrenaline is in high dose, which receptor is more sensitive?
Alpha
When adrenaline is in low does, which receptor is more sensitive?
Beta
When adrenaline is administered, what happens when it binds to a1, b2?
a1: vasoconstriction
b2: increased blood flow to skeletal muscle, bronchodilation
Adrenaline is used in
Anaphylactic shock, status asthmaticus
NA does not act on
B2
NA acts on a1 and b1, which brings about what effects?
a1: vasoconstriction, BP increases (reflex bradycardia)
b1: CO increases, systolic BP increases
Dopamine produces dose dependent effects, in low, moderate and high does, what effects are produced respectively?
Low (D1): increase renal blood flow
Moderate (B1): increase cardiac output
High (a1): vasoconstriction
Isoproterenol acts on b1 and b2, what effects does it produce?
b1: increase HR, increase CO
b2: TPR and diastolic BP decrease drastically
*b1=heart
b2=blood vessels & bronchioles
Directly acting adrenergic drugs which are selective include
phenylephrine (a1) , clonidine (a2) , dobutamine (b1) , salbutamol (b2)
Phenylephrine acting on a1 has effects of?
Vasoconstriction: increase BP
Mydriasis(pupil dilation) ONLY
Clonidine (a2) causes
Decrease BP: bradycardia
Prevent release of NA
Clonidine is used to treat
Hypertension
Dobutamine (b1)
Increase HR and CO
Salbutamol (B2) causes
Smooth muscle to dilate
Bronchodilation
Vasodilation
Uterine relaxation
Salbutamol/ albuterol (b2) treats
Bronchial asthma
Preterm labour
State which are inhibitory which are stimulatory adrenergic receptors, and their common effects
a1 + : blood vessels (vasoconstriction), pupil (dilation)
a2 - : inhibit neuro transmission, insulin
b1 + : heart, renin
b2 - : blood vessel (vasodilation), bronchiole (dilation)
b3 -
Indirectly acting adrenergic agonists are divided into
releasing agent
uptake inhibitor
MAO/COMT inhibitor
Under indirectly acting adrenergic agonists, releasing agent includes
Amphetamine: stimulate release of catecholamines
Effects on:
CNS=delirium
CVS= increase BP
Uptake inhibitors include
Amitriptyline:improve mood, tachycardia, blocks reuptake of NA
Cocaine
MAO/COMT inhibitors:
MAO present intracellularly and metabolise catecholoamines,COMT present extracellularly and metabolise catecholamines.
Example: selegiline
It inhibits degradation of Dopamine by inhibiting MAO-B (PARKINSON DISEASE)
MAO-A inhibitors: increase synaptic NA con. by inhibiting degradation (DEPRESSION)
Mixed acting adrenergic agonist is
ephedrine ( a1 a2 b1 b2)
non selective
Increase NA release
Increase TPR, CO HR
bronchodilation
CNS stimulation
B2
Bronchodilation
