Sympatholytics Flashcards
What are the 3 classes of sympatholytics?
peripheral adrenergic receptor blocker
central α2 agonists
neurotransmitter depleters
What are the subclasses of the peripheral adrenergic receptor blockers?
α1 blockers
β blockers
mixed α + β blockers (vasodilating β blockers)
What are the α1 blocker agents?
Prazosin
Terazosin
Doxazosin
α1 receptor antagonists block what?
post-synaptic α1 receptor
α1 receptors naturally cause vaso________ on vascular smooth muscle.
vasoconstriction
Blocking the α1 receptor causes what?
vasodilation
The decrease in BP from α1 blockers initially causes ________ _________.
sympathetic stimulation or baroreceptor reflex
What are some results of sympathetic stimulation?
Increased HR and CO
Increase in plasma renin activity/release
In the use of α1 blockers renal blood flow is _______.
unchanged
α1 blockers can cause ______ _______, or what is known as the “first dose effect”.
postural hypotension
Inhibition of smooth muscle contraction with the use of α1 blockers occurs in what other areas of the body?
urinary bladder sphincter
prostate
seminal vesicles
uterus
What other conditions are α1 blockers indicated?
BPH
What are the adverse effects of α1 blockers?
Peripheral vasodilation: dizziness, postural hypotension, edema, palpitations, fatigue, nasal congestion
Anaphylaxis
Priapism
What are some drug interactions with α1 blockers?
combining with other antihypertensives can cause hypotension
Verampamil causes increased Terazosin levels
What is the ending for α1 blockers?
-zosin
What groups are α1 blockers contraindicated?
pregnancy
those with pheochromocytoma (adrenal tumor)
α1 blockers are/are not recommended for monotherapy?
are not
What populations may benefit from α1 blockers over other agents?
HTN diabetics
gout
BPH
What are the β blocker agents?
Propranolol
Metoprolol
Atenolol
What is the ending for β blockers?
-olol
What is the MOA for β blockers?
Blocking the β receptors reduces cardiac contractility and HR to reduce CO. β blockers also reduce the secretion of renin and lower plasma Ang II levels.
What is the most effective β blocker in treating HTN?
They are all equally effective.
How do β blockers effect the BP in normotensive patients?
no change
Pure β receptor antagonists _____ CO and cause and immediate reflex _______ in TPR.
reduce
increase
Partial β receptor antagonists produce a ______ in CO but BP falls due to a _______ in TPR.
lesser decrease than pure β receptor antagonists
decrease
What are the vasodilating β blockers?
Labetolol
Carvedilol
Nebivolol
Vasodilating β blockers provide effective therapy in what stages of HTN?
all stages of HTN
In what cases are β blockers an appropriate first choice therapy?
post MI
heart failure
arrhythmias
angina
Can you combine β blockers with ACEIs or ARBs?
no - its redundant
Are diuretics needed in combination with β blockers?
no
What are the adverse effects of β blockers?
bronchoconstriction
bradycardia
masks symptoms of hypoglycemia
fatigue/dizziness/depression
Which subclass of sympatholytics are preferred in diabetics?
Vasodilating β blockers
What are the dosing considerations for β blockers?
start low, titrate up, titrate down
What drug interaction blunts the hypotensive effect of β blockers?
NSAIDS
What drug interaction can cause a hypertensive crisis?
epinephrine
What is the most concerning ADR with β blockers?
New onset diabetes
What conditions are the use of β blockers most supported in?
heart failure
post MI
What are the central α2 agonist agents?
α-methyldopa
clonidine
guanabenz
guanfacine
What is the MOA of central α2 agonists?
By acting on the presynaptic α2 receptor, central NT release is decreased. Sympathetic outflow is reduced and BP is decreased.
Why are central α2 agonists not 1st line?
ADRs
Methyldopa is an analog of what?
DOPA
What is the MOA of methyldopa?
Acts in the brainstem to reduce sympathetic outflow
Is methyldopa degraded by monoamine oxidase?
no
Methyldopa has _____ effect on CO and HR except in _____.
little
elderly
In the use of α2 agonists the baroreceptor reflex is ____ ______.
turned down
In the use of α2 agonists, renal blood flow and function is ________.
unaffected
In the use of α2 agonists plasma renin levels ______.
decrease
α2 agonists should be combined with _______ to maintain efficacy.
diuretic
What medication is preferred for HTN in pregnant women?
Methyldopa
What are the adverse effects of Methyldopa?
CNS: sedation, depression, dry mouth, ↓ libido, Parkinsonian signs, hyperprolactinemia, bradycardia
Hepatotoxicity
Hemolytic anemia
α2 agonists _____ CO and ______ TPR.
decrease
decrease
Guanfacine is _____ selective for α2 receptors than clonidine and guanabenz.
more
Which α2 agonist is available in a patch?
clonidine
What are the adverse effects of α2 agonists?
CNS: sedation, dry mouth, sleep disturbances, bradycardia, sexual dysfunction
What is a main concern about discontinuing α2 agonists?
withdrawal syndrome
What does α2 agonist overdose look like?
opioid overdose
What are the minor sympatholytic agents?
Guanadrel
Reserpine
Guanadrel specifically targets what?
postganglionic adrenergic neurons
Guanadrel is taken up into ________ via the ___ _____.
presynaptic terminal
NE transporter
Guanadrel ______ NE in NT granuals.
replaces
Guanadrel has ______ agonist activity.
no
What drug interaction will blunt effectiveness of Guanadrel?
TCAs
cocaine
chlorpormazine
What population is Guanadrel contraindicated?
pheochromocytoma
CHF
Guanadrel causes vaso_____, __ TPR, minor __ in renal blood flow and GFR.
vasodilation
decrease
decrease
What are the adverse effects of Guanadrel?
orthostatic hypotension
exercise intolerance
volume expansion
weakness, lassitude, sexual dysfunction, diarrhea
Guanadrel is not used as monotherapy due to what?
orthostatic hypotension
Reserpine binds to ___ ______ _____.
NT storage vesicles
Reserpine impairs ______, ________, ________ neurotransmission.
adrenergic
dopaminergic
serotonergic
Reserpine depletes NTs peripherally, centrally, or both?
both
Reserpine ___ TPR ___CO ___HR
decreases
decreases
decreases
In the use of Reserpine, orthostatic hypotension is/isn’t a problem.
is not
In the use of Reserpine, plasma renin levels ______.
decrease
What are the adverse effects of Reserpine?
sedation, inattention, nasal congestion, sexual dysfunction, suicidal depression
Reserpine should/shouldn’t be combined with a diuretic?
should