lecture 41 Flashcards
What are some examples of disorders that can be treated with adrenergic agonists and antagonists?
- hypertension
- angina
- heart failure
- arrhythemia
- asthma
- migraine
- anaphylactic reactions
what body hormone has little affect on B2 receptors?
Norepinephrine has little effect on beta2 receptors,
therefore it cannot cause bronchodilation, because
receptors in bronchial smooth muscle are beta2
on the other hand, epinephrine is a potent bronchodilator
What receptors are abundant in skin blood vessels
alpha 1 receptors
norepinephrine and epinephrine cause constriction of such vessels.
what receptors are found in the smooth muscle of blood vessels in skeletal muscle
both alpha 1 and and beta 2
Activation of beta2 receptors causes vasodilation.
Activation of alpha1 receptors causes vasoconstriction
What does a low dose of epinephrine do?
vasodilation
what does a high dose of epinephrine do?
vasoconstriction
what are the three types of adrenergic agonists?
- direct acting
- indirect acting
- mixed
What are the three types of direct acting adrenergic agonists?
- endogenous catecholamines
- Beta adrenergic
- alpha adrenergic
what are the three endogenous catecholamines?
- epinephrine
- norepinephrine
- dopamine
what are the effects of epinephrine?
acts as a hormone
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 lipolysis (alpha 1 and beta 2 effect).
How does a large dose of epinephrine have on blood pressure?
blood pressure is increased
- increased venticular contraction
- increased heart rate
- vasoconstriction
How does a small dose of epinephrine have on blood pressure?
- peripheral resistance decreases
- systolic pressure decreases
- heart rate increases
no mean increase in bp
What are the uses of epinephrine?
- anaphylactic shock
- acute asthmatic attack
- cardiac arrest
norepinephrine is an an agonist at what receptors?
alpha 1 +2 and beta 1
little effect on beta 2
effects of norepinephrine?
Causes peripheral vasoconstriction (α1 effect).
Increases cardiac contractility (β1 effect).
Systemic administration of norepinephrine
increases peripheral vascular resistance, systolic
blood pressure and diastolic blood pressure.
The increase in blood pressure stimulates
baroreceptors leading to reflex bradycardia.
what is use for norepinephrine?
to treat shock
what is the baroreceptor response to increased blood pressure?
stimulates the parasympathetic activity and inhibits the sympathetic activity
decrease heart rate and decrease force of contraction
what is the baroreceptors response to decreased blood pressure?
inhibits parasympathetic and activates sympathetic
increased heart rate and increased force of contraction
isoproterenol
non selective beta 1 and 2 adrenergic agonist
the use of isoproterenol?
Isoproterenol may be used in emergencies to
stimulate heart rate in patients with bradycardia
or heart block.
Dobutamine
beta 1 selective adrenergic agonist
given by IV
uses for dobutamine?
Management of acute heart failure.
Management of cardiogenic shock.
albuterol
beta 2 adrenergic agonist
uses for albuterol
Causes bronchodilation (beta 2 effect).
Used in asthma.
DOC for acute asthma attacks
what is phenylephrine and what is it used for?
alpha 1 selective adrenergic agonist
causes vasoconstriction
use:
Nasal decongestant. Given orally or topically.
Mydriatic.
What is clonidine and what is it used for?
partial alpha 2 adrenergic selective agonist
centrally acting anti-hypertensive
What are the two indirect acting adrenergic agonists (releasing agents)?
- amphetamine
2. tyramine
What is amphetamine and what is it used for?
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
Where is tyramine found?
found in fermented foods such as cheese and wine
MAO inhibitor = antidepressant
What is an uptake inhibitor (indirect acting adrenergic agonist)
cocaine
blocks the reuptake of monoamines
leads to monoamine accumulation in the synapse
what are the two mixed acting adrenergic agonists?
ephedrine and pseudoephedrine
What is ephedrine and what is it used for?
Not a catecholamine
poor substrate for COMT and MAO long duration.
Penetrates the CNS.
USES
Used as a pressor agent, particularly during
spinal anesthesia.
What is pseudoephedrine used for?
decongestant
What are the three types of adrenergic antagonists?
- alpha
- beta
- partial
what are the two kinds of alpha adrenergic antagonists?
- non-selective alpha
2. alpha 1 selective
what are the two kinds of beta adrenergic antagonists?
- nonselective beta
2. beta 1 selective
What are two non-selective alpha adrenergic blockers?
- phenoxybenzamine
2. phentolamine
what is phenoxybenzamine and what is it used for?
Irreversible antagonist at alpha 1 and alpha 2 receptors.
Unsuccessful for hypertension.
USES
Used in Pheochromocytoma: Prior to surgical
removal of the tumor.
what is phentolamine and what is it used for?
Reversibly antagonist at alpha 1 and alpha 2 receptors.
USES
Pheochromocytoma: control of hypertension during preoperative preparation and surgical excision.
Hypertensive crisis due to stimulant drug overdose
what is prazosin and what is its uses?
selective blocker of alpha 1 adrenergic receptors
lowers blood pressure
uses:
used for the treatment of hypertension BUT is not the drug of choice
BPH: benign prostatic hyperplasia
DOC for symptom relief
improve urinary flow
what are the effects of beta blockers?
Slow heart rate and decrease myocardial contractility (b1 effect).
Blockade of b2 receptors in the lungs can cause respiratory crisis in patients with COPD or asthma.
lower Glycogenolysis (b2 effect)
lower Glucagon secretion (b2 effect)
What are the uses of adrenergic beta blockers
Hypertension Stable Angina Pectoris Myocardial Infarction Atrial Fibrillation Hyperthyroidism Glaucoma Migraine prophylaxis Performance Anxiety (“Stage Fright”)
atenolol description and uses?
beta 1 adrenergic blocker
Useful in hypertensive patients with impaired
pulmonary function.
Useful in diabetic hypertensive patients.
What are the adverse effects of using adrenergic beta blockers?
bronchoconstriction
hypoglycemia
CNS: sedation dizziness lethargy fatigue
what is pindolol and what is it used for?
It is a partial beta agonist (adenergic)
May be preferred in individuals with diminished
cardiac reserve or a propensity to bradycardia.
