Sympathetic Drugs Flashcards
(36 cards)
Why is it important find the Goldylocks zone for Sympatheric drugs without the reflexive bradycardia (ex: Norepinephrine, Phenyephrine)?
Sympathetic Drugs often used to increase BP to ensure O2 perfusion to organs.
BP=cox resistance
CO= HRx SV.
Sympathetics drugs affect the SV by
1) increasing preload (vasconstrinction (peripheral resitance)–> increase BP–> more blood gets return to the heart–> increase SV.
-via a1
2) increasing contractility–> more blood pumped out of heat–> increase SV .
- B2
3) Decrease afterload ( reflexive bradycardia)–>less resitance to leave–> more blood leaves heart–> higher SV
. only norep + phenyephrine
The importance in finding the balance is especially important for drugs with A1 and B2
. epinphrine
these drugs do not cause as strong of a constriction as norep therefore do not get reflexive bradycardia
. as a result the afterload will stay high and this will make the heart work harder which is not ideal
. a balance between preload ( constriction) and afteload (reflexive bradycardia)
What are the preferential recptors for
1) epinephrine
2) norepinphrine
3) Isoproterenol
4) Dopamine
5) Dobutamine
1) epinephrine–>a1 ( some b1,B2)
2)norepinphrine–> a1
3)Isoproterenol–> B1,B2
4) Dopamine–> targets different receptos based on dose
. high dose- a1
.med dose- b1
.low dose-dopamine
5) dobutmaine–> B1
Which sympathomimetics increase contractility of the heart ( B1)?
1) Isoprotenol
. B1, B2
2) Dobutamine
. b1
3)Dopamine
.medium dose b1
3) epidrine ( mixed sympathomimetic)
Which catecholamines and non catecholamines cause vasoconstriction?
1) epinephrine (catecholamine)
.a1
.B2
2) norep (catecholamine)
.a1
3) Dopamine ( catecholamine)
. high dose a1
4) phenylephrine ( non catecholamine alpha agonist)
Use of epinphrine vs nor epinphrine
noepinephrine
1) 1st line vasopressor
. brings a1 only–> reflexive bradycardia
. USE IN SEPTIC PATIENTS, VERY ILL PATIENTS
epinephrine
1)2nd line vasopressor or CATS
.a1
.B2
2) anaphylaxis
3)local vasoconstriction
. useful to stop epistaxis
.useful to keep a drug in local tissue longer ( lidocaine)
What are the physiological ways to deal with hypotension and correlate to drugs that have these effect?
BP= CO x peripheral resitance
CO= HR x SV
BP=COx peripheral resitance
CO= HR x SV
SV has 3 components that can be addressed
1) preload—> venous vasoconstriction a1
. push more blood back to heart
drugs
a) norepinphrine ( 1st line)
b)epinphrine (2nd line)
c)dopamine ( hgih dose)
- drug of choice post cardiac arrest
d) Ephedrine ( mixed sympathomimetic increase NE and binds to A1+ B1 as well)
e) phenylephrine
2) Afterload–> arterial resitance the makes it harder to blood to leave the heart
. want to decrease this by choosing drugs with reflexive bradycardia
drugs
a)norepinephine is able to kick in the reflexive bradycardia
c)Phenylephrine
. can kick in reflective bradycardia
3) contractility–> making the heart pump with moire force–> more blood leave the heart–> B1
drugs
. NOT norepinephrine
a) Dobutamine(stongest iontrophic, increase contractility)
b) isoprotanerol
c) dopamine medium dose
d) ephedrine
HR can be addressed by
a) atropine ( parasympathilytics)
b) glycopyrate ( parasympatholytic)
c) Dobutamine ( moderate effect)
You have a patient under anestesia that you give a vasopressor to ( norepinephrine , dopamine) you see they develop an arrythmia what do you do?
Arythmias / tachycardia can occur when giving sympathomimetics like a vasopressor.
These are short-acting drugs–> eliminated fast
Solution: stop the drug and see if this helps the arrhythmia
. if it doesnt, then try antiarrhythmia drugs
What are the vasconstriction drugs with no B2 action?
1) norepinprhine ( catecholamine direct sympathomimetic)
2) phenylephrine ( no catecholine direct sympathomimetic)
Different receptors catecolamines binds to and their actions/ clinical use associated with it?
. epinpeohrine
. norepinephrine
.dopamine
.isoprotenol
.Dubutamine
Epinephrine
.a1–> vasoconstion
1) second line vasopressor in cpr or Cats
2) local tissue vasoconstriction to medication there longer ( ex: lidocaine)
.B1–> chrontropy negligable
.B2–> prevent degranulation mast cells–> anphylaxis
Norepinephrine
a1–_ vasconstriction
.first line vasopressor CPR becasue for reflexive bradycardia
Dopamine
.high doses a1–> vasopresspr–> drug of choice for post CPR
. low doses binds D1–> vasodilation but impossible to do in the real world
Isoprotenol
.B1–> increase contracility–>increase BP
. increase BP when low BP is due to lack of contractility
.B2–> brocnhdilation
Dobutamine
.B1-> increase contractility–> increaase BP
- use when low Bp due to lack of contractility
-drug of choice dilated cardiac myopathy
Dopamine is used as a vasopressor but in what specific case is it favoured in?
. post cardiac arrest
How are Isoprotrenol and Dobutamine similar/ different ( recptors? clinical use)?
Similar
. both catcholamines–> agonist to adrenergic receptors
Different
1) binds different receptors
. Isoprotenol: B1 + B2
- use: increase contractility + bronchodilation
Dobitamine: B1 only
-use: increase contractility ( drug of choice dilated cardiomyopathy)
What are sympathomimetics generally used for?
Sympathomimetics can be
. direct acting –> catecholmines
.non catcholamines
.mixed
1) increase BP
. by either increasing peripheral restance via vasoconstriction –> a1
. decrease afterload
-strong vasopressors ( norep, phenylepinephrine)
.increase contractility
- B1
2) Bronchodilation–> B2
3) urine incontinence–> a1
How is phenylephrine similar/different to noepinephrine and epinephrine?
.family
.receptors
.action/clinical use?
Phenylephrine
. non catecholamine sympathomimetic
. agonist to a1
. use:
1) vasopressor that allow for reflexive bradycardia
2) local vasoconstiction
3) mydriases–> treatment open angle glaucoma
norepinephrine
.catecholamine sympathomimetic
.agonsit to a1
. use:
1) first line vasopressor
epinephrine
.catecholamine sympathomimetic
.agonsti a1, b1, b2
.use:
1) 2nd line vasopressor
2)local vasoconstriction
3) anaphylaxis
Clinical use Albuterol, Clenbuterol, Terbutaline?
. drug class
. receptors bind
. action/ clinical use
.non catecholamines B agonists
.agonsits B2, B1
-not all bind to B1 (ranked from least to most binding B1)
-albuterol->terbutaline–>clenbuterol-
.use: bronchodilation ( asthm)
-cats
-horses
tachycardia is a side effect but mostly with the ones that bind to B1–> especially clenbuterol
what are the parasympathomimetics/lytics and sympathomomimetics drugs of the bladder? how do they work?
.bethanacol
.propanthelin
.phenypropanolamine
.phenoxybenzamine
.prazosin
.tamulosin
Parasympatomimetics will allow to pee by contractin detrusor
1) Bethanacol
. parasympathomimetic
. agonist to M detrusor–> use for detrusor atopy
parasympatholytics–> cause sympathetics action–> no pee by relaxing detrusor
2) Propantheline
.parasympatholytic
. antagonist M recprtor detrusoe–> relax bladder
-use for over active bladder
Mixed symapthomimetics–> no PP
3)phenylpropanolamine (PPA)
. mixed sympathomimetic
. increases EP + agonsit to a1
. use: maintain tone internal sphinter bladder–> urethral sphincter incompetence due to low estrogen
a1 sympatholytics–> pee by dilating sphincter
4)phenoxybenzamine
. a1 sympatholytic
.antagonist a1
.Use: relax internal spincter–> use when not peeing becasue urethral hypertonicity
5) Prazosin
.a1 sympatholytic
.anatagonist a1
.Use: relax internal spincter–> drug of choice of feline ideopathic cystitis
6) Tamulosin
.a1 sympatholytic
.Use: relax upper urinary tract urethra useful for prostatis, stone blocking urethers
what use to treat feline idopathic cystitis?
Prazosin
Contraindications Prazosin?
. drug class/ MOA how this explains contradictions
Prazosin a1 sympatholytic
. relaxes a1 spincter bladder
. but also causes vasodilation
1) dont use if blocked patient with renal disease
. further hypotension–> ischemia kidneys
2)preexisting hypotensive patient
3) heart disease with bradycardia+ arrythmias
4) bronchospasms
. enhances parasympathic activity–. bronchospams
Differences and similariteis between Phenoxybenzamine,prazosin and tamulosin?
. drug class/ MOA
.clinical use
All a1 sympatholytics
. used mainly to relax the spincters + dilate urethra to favour PP
pheno
1) treat pheochromocytoma
2) dilate interal spincter
prazo
1) dilate internal spincter drig choice feline cystitis
2) pulmonary hypetension
tamuline
1) dilate upper urinary tract–> prostitis, stones in urethers
What are the different types of sympathomimietics? Name the drugs in the classes
1) catecholamine ( agonists to the adrenergic receptors)
.ep
.norep
.dopamine
.dobutamine
.isoprotrenol
2) non catecholamine alpha agonists
. phenylephrine
3) non catecholamine beta agonists
.ractopamine, Zilpaterol
.Albuterol, clenbuterol, Terbutaline
4) mixed.indirect sympathomimetics
.phenylpropanolamine (PPA)
.ephedrine
what are the different types of sympatholytics? names drugs in the different classes?
1) a1 sympatholytics
.aginst a1
2)B1 sympatholytics
.agonist B1
Contraindication for norepinephrine and Phenylephrine?
1) already hypertensive patients
.Bind only to a1–> very strong vascoconstriction
additionally phenyleprine
. no renal patients due to possiblity too much vasoconstriciton–> ischmeia kindey
how do mixed sympathomimetics work? give example of drugs?
Mixed sympathomimetics work
1) directly agonsit to adrenergic receptor
2) increase catecholamine
Phenylpropanolamine
Ephedrine
What are parasymptomimetics? give the different mechanisms and drugs?
Parasynpathomimetics are drugs that enhance parasympathetic activity
1) Direct
.agonist to Muscarinic or Nicotinic recptors (choline esters)
- Bethanacol
2) indirect
antagonist to acetylcholinesterase ( cholinesterase inhibitors)–> increasing Ach
1)neostigmine
2)pyridostigmine
3)edrophonium
what are parasympatolytics?
Parasympatolytics are drugs that block parasympathic activity–> enhance sympathetic activity
Example
1) Atropine
2) Glycopyrolate
3)propanthelin
