Adrenoceptor agonists and Sympathomimetics Flashcards
Activation of sympathetic system leads to…
epinephrine release from the adrenal medulla
What is the primary neurotransmitter of the Sympathetic nervous system(SNS)?
Norepinephrine at postsynaptic sympathetic synapses
Tissues acted on by alpha one receptors and the effects at those tissues…
- vascular smooth muscle – contraction
- genitourinary smooth muscle – contraction
- intestinal smooth muscle – relaxation
- heart – Inc. in inotropy and excitability
- liver – glycogenolysis and gluconeogenesis
Tissues acted on by alpha 2 receptors and the effects at those tissues…
- Pancreatic Beta cells – dec. insulin secretion
- Platelets – aggregation
- nerve – dec. norepinephrine release
- vascular smooth muscle – contraction
Tissues acted on by beta-1 receptors and the effects at those tissues…
- heart – inc. chronotropy and inotropy;
inc. AV node conduction velocity - renal juxtaglomerular cells – inc. renin secretion
tissues acted on by beta-2 receptors and the effects on those tissues…
- smooth muscle – relaxation
- liver – glycogenolysis and gluconeogenesis
- skeletal muscle – glycogenolysis and K+ uptake
tissues acted on by beta-3 receptors and the effects on those tissues…
Adipose – lipolysis
What is the mode of action of a direct sympathomimetic?
directly binds to and activates adrenoceptors on target tissues
What is the mode of action of indirect sympathomimetic agonists?
enhance the activity of endogenous catecholamines
What 2 ways do indirect sympathomimetic agonists enhance activity of endogenous catecholamines?
- by displacing endogenous catecholamines from presynaptic nerve terminals
- by decreasing clearance of synaptic catecholamines
Which adrenergic receptor increases PVR as well as increasing CO due to increased VR?
alpha-1
Which adrenergic receptor causes contraction of pupillary dilator muscle?
alpha-1
Which adrenergic receptor erects hair via pilomotor smooth muscle?
alpha-1
Which adrenergic receptor causes contraction of the prostate?
alpha-1
Which adrenergic receptor increases force of contraction in the heart indirectly due to increased venous return (VR)?
alpha-1
Which adrenergic receptor inhibits transmitter release in adrenergic and cholinergic nerve terminals?
alpha-2
Which adrenergic receptors causes inhibition of lipolysis in fat cells?
alpha-2 (B3 stimulates lipolysis)
Administration of a pure alpha-2 agonist (increases/decreases) sympathetic tone due to inhibitory effects in CNS.
decreases
Which adrenergic receptor increases force (inotropy) and rate of contraction (chronotropy) in the heart?
beta-1
Which adrenergic receptor relaxes smooth muscle in respiratory, uterine, and vascular smooth muscle?
beta-2
which adrenergic receptor activates glycogenolyis in the human liver?
beta-2
Which adrenergic receptor promotes potassium uptake in skeletal muscle?
beta-2
Which adrenergic receptor dilates renal blood vessals in smooth muscle?
dopa-1
Which adrenergic receptors may induce natriuresis?
dopa-1 receptors
Which adrenergic receptors improve kidney perfusion?
dopa-1
Which adrenergic receptors modulates transmitter release in nerve endings?
dopa-2
Presynaptic Dopa-2 receptors (increase/decrease) norepinephrine release?
decrease
Adrenoceptors can be (sensitized/desensitized) after exposure to catecholamines and other sympathomimetic drugs.
DESENSITIZED
Adrenoceptors can be (downregulated/upregulated) after prolonged periods of deinnervation.
upregulated
Alpha receptors (increase/decrease) arteriolar resistance and (increase/decrease) venous capacitance.
increase arteriolar resistance
decrease venous capacitance
Skin and splanchnic vessels have predominantly which adrenergic receptors?
alpha
Beta receptor activation results in (increased/decreased) calcium influx in cardiac cells?
increased
What is the effect on blood pressure by pure alpha agonist stimulation?
increase in BP (due to incr. PVR and dec. venous capacitance)
What is the effects on MAP by pure beta agonist stimulation?
overall decrease (due to inc. in CO which maintains systolic BP and decreases diastolic BP)
What are the alpha sympathomimetic effects on the eye?
Alpha agonists cause mydriasis and reduce intra-ocular pressure by increasing the outflow of aqueous humor.
T/F: beta agonists have little effect on intra-ocular pressure.
FALSE (Beta agonists have NO effect)
What is the effect that beta-2 sympathomimetic receptors have on the respiratory tract?
bronchodilation
Which adrenoceptors are used to treat asthma and COPD?
beta-2
T/F: Adrenoceptor stimulations have decongestant action due to the presence of alpha receptors.
true
How do alpha stimulants effect the GI tract?
relax the smooth muscle INDIRECTLY by presynaptically reducing the release of ACh.
How does beta stimulants effect the GI tract?
Relax smooth muscle DIRECTLY via hyperpolarization and decreased spike activity in these cells.
Which adrenoceptors are useful in pregnancy?
beta
Which adrenoceptor types does the uterus contain?
alpha and beta-2
Ejaculation is dependent upon activation of which adrenoceptors?
alpha
T/F: Certain sympathomimetic drugs can cause dry mouth, but the mechanism is unkown.
TRUE (ex. clonidine)
Sympathomimetic drugs increase sweat production from which sweat glands that respond to stress?
apocrine (remember eccrine are stimulated by muscarinic cholinoreceptors)
Renin secretion is inhibited by which adrenoceptors?
alpha-2
____ is a very potent vasoconstrictor and cardiac stimulant.
Epinephrine
What is often used to reduce blood flow to certain areas, like nosebleeds?
epinephrine
Henry is allergic to bees and while playing in the park gets stung and goes into anaphylaxis. What is used at the initial treatment for his anaphylaxis?
Epinephrine
Norepinephrine is also known as….
Levarterenol
Norepinephrine is used to treat…
HYPOtension
Which adrenoceptors does NE have little effect on?
beta-2
What is the immediate metabolic precursor to NE?
Dopamine
At regular doses, what receptors does dopamine activate?
D-1 leading to vasodilation as well as B-1 in the heart
What is the effect of dopamine at high rate?
causes vasoconstriction particularly in the renal vascular bed
Which sympathomimetic is used to treat cardiogenic shock?
dopamine
Which sympathomimetic is an important neurotransmitter in CNS that mediates reward, coordinated movement, and mood?
Dopamine
Which sympathomimetic is a relatively pure alpha agonist?
Phenylephrine
Which alpha sympathomimetic is used to treat miosis and is an effective decongestant?
Phenylephrine
Heather is about to undergo a retinal exam, which ophthalmic agent would you use before administering the exam?
Phenylephrine
A patient comes in with symptoms of Horner’s syndrome and you are wanting to localize the lesion, which sympathomimetic would you use to do so?
Phenylephrine
A patient with a history of HTN comes in to the clinic complaining of nasal congestion, when selecting a decongestant for this patient why would you want to be careful about prescribing Phenylephrine for them?
because Phenylephrine can raise BP
Which sympathomimetic is a prodrug that is hydrolyzed to an alpha-1 agonist?
Midodrine
A 25 year old male presents to the clinic complaining of fatigue that worsens upon laying down. He says he feels slightly better when sitting up. You check his vitals and he has a HR of 68 and a BP of 90/65. Which sympathomimetic do you prescribe him?
Midodrine
Which sympathomimetic acts like phenylephrine since it is an alpha-1 agonist but is only used clinically in hypotensive states?
Methoxamine
Which sympathomimetic is the prototypical alpha-2 agonist?
clonidine
A 35 year old diabetic with uncontrolled HTN comes into your clinic complaining of diarrhea. Which adrenergic agonist would you prescribe them?
Clonidine (may have some efficacy in diabetics with diarrhea due to autonomic neuropathy)
A patient comes into the clinic and upon taking their vitals you discover their BP is 175/125. Upon further investigation the patient tells you that they have been taking a little white pill for their blood pressure but can’t remember the name of it. Which medication do you suspect that they were taking?
clonidine (can cause severe rebound HTN if not tapered off of)
A 35 year old male who has been smoking 2 packs a day for the last 10 years comes in to the clinic because he is trying to quit smoking but is having major nicotine cravings. What adrenergic agonist medication would you prescribe for him?
Clonidine
A 50 year old female presents to the clinic with the beginning stages of menopause. She complains of having hot flashes nightly and asks is there anything you can do for them. Which adrenergic agonist would you prescribe that would diminish these hot flashes?
Clonidine
Which two alpha-2 agonists can be used to treat glaucoma?
Apraclonidine and Brimonidine
Which sympathomimetic drug is a central acting alpha-2 agonist that is used for sedation of intubated patients?
Dexmedetomidine
Which direct acting alpha agonist may cause hypotension if given in large doses because of its central, Clonidine-like effects?
Oxymetazoline
Which two adrenergic agonists are used as topical decongestants due to their ability to promote constriction of nasal mucosa?
Xylometazoline and Oxymetazoline
Which two sympathomimetic drugs are direct acting alpha agonists?
xylometazoline and oxymetazoline
Which sympathomimetic drug is very potent on beta receptors but has little effect on alpha receptors?
Isoproterenol
Isoproterenol is a potent (vasodilator/vasoconstrictor) because it acts mainly on beta receptors.
vasodilator
Which sympathomimetic drug causes a marked increase in CO associated with a fall in diastolic BP and a slight increase in systolic BP?
Isoproterenol
Which sympathomimetic drug can be used to treat cardiogenic shock or even in heart failure due to its positive ionotropic effects?
dobutamine
Which receptor does Dobutamine activate?
Dobutamine is also a relatively selective ____ agonist.
Alpha 1- receptors; Beta 1 agonist
Terbutaline and Ritodrine are ______ selective agonists.
Beta-2 agonists
Which sympathomimetic drug is used to treat asthma?
Terbutaline
Which sympathomimetic drug is used to relax the uterus during labor?
Ritodrine
What causes selective vasodilation and is used in IV to treat hypertension?
Fenoldopam
Fenoldopam is a ___________ agonist.
D-1 agonist
What are the 5 Indirect sympathomimetic drugs that are Amphetamine like or “displacers”.
- Amphetamine
- Methamphetamine
- Methylphenidate
- Modafinil
- Tyramine
What are the 2 indirect sympathomimetic drugs that are reuptake inhibitors?
- Antidepressants
2. Cocaine
What drug is misused often as a CNS stimulant?
Amphetamine
Which indirect sympathomimetic drug enters the CNS quicker than ephedrine and causes a stimulation in mood an alertness and suppression of appetite?
Amphetamine
Which 2 drugs that are like amphetamine have some efficacy in kids with ADHD?
Methylphenidate (Ritalin) and Pemoline
What other drugs were listed in the notes that are like Amphetamine?
Methamphetamine Phenmetrazine Methylphenidate (Ritalin) Modafinil Pemoline
Which indirect sympathomimetic drug is a new amphetamine substitute used to treat narcolepsy?
Modafinil
Which indirect sympathomimetic drug has appetite suppression effects that may be useful against fighting obesity and useful against ADHD in children?
Modafinil
Which indirect sympathomimetic drug is found in high concentrations in cheese and other fermented foods?
Tyramine
What readily metabolizes Tyramine? Why is this a problem?
MAO in the liver. It is a problem if a patient is on MAO inhibitors (certain antidepressants), it will not be metabolized and can result in marked increases in BP.
A patient on MAO inhibitors and Tyramine will have what side effect?
High blood pressure - “Tyramine toxicity” or “cheese toxicity”
Which indirect sympathomimetic drug acts like norepinephrine (this is a stimulant)?
Tyramine
Which indirect sympathomimetic drug is a local anesthetic, can be used to decrease blood flow, and thus is a useful in cases of nosebleeds?
Cocaine
Which indirect sympathomimetic drug results from inhibition of transmitter (dopamine) reuptake at noradrenergic synapses?
Cocaine
Which indirect sympathomimetic drug has an amphetamine like effect that is quicker and more intense?
Cocaine
Which indirect sympathomimetic mimetic drug inhibits dopamine reuptake in the brain?
Cocaine
What are the 3 “mixed acting sympathomimetic” drugS?
- Ephedrine
- Pseudoephedrine (Sudafed)
- Phenylpropanoleamine (Accutrim)
Which mixed acting sympathomimetic drug is a mild stimulant because it gains access to the CNS and was once used for asthma?
Ephedrine
Which mixed acting sympathomimetic drug is a component of the herbal medication Ma huang?
Ephedrine
Which mixed acting sympathomimetic drug is now restricted because it is a precursor to methamphetamine
Pseudoephedrine (Sudafed) is one of its enatiomers?
Which mixed acting sympathomimetic drug was a component of OTC appetite suppressants? Removed from market because of increased risk of hemorrhagic stroke in females?
Phenylpropanoleamine
What are the effects in toxicity of sympathomimetic drugs?
Cardiac effects
- increased cardiac work
- leading to ishemia and failure
- myocardiac damage
- sinus tachycardia
- ventricular arrhythmias
What can be used to reverse the toxicity of sympathomimetic drugs?
antagonists
Which drug overdose may cause paranoid state?
Amphetamine
Which drug overdose can cause convulsions, tremors, and even MI and coma?
cocaine