ANS pharmacology & pathophysiology 4 Flashcards
Which is NOT a competitive inhibitor of acetylcholine?
a. atropine
b. nicotine
c. scopolamine
d. glycopyrrolate
b. nicotine
Cholinergic agonists mimic the actions of
ACh but differ in their nicotinic and muscarinic activities
Muscarinic antagonists like atropine are
competitive inhibitors of ACh at parasympathetic muscarinic receptors
Side effects of muscarinic antagonists include
tachycardia
dry mouth
decreased GI motility
bronchodilation
A common self-administered cholinergic agonist is
nicotine
Ganglia of __________ are activated by nicotine
the SNS and PNS
In the CV system, nicotine’s effects lead to
unopposed sympathomimetic activity causing the vascular tone to increase
Other examples of cholinergic agonists include
methacholine
bethanachol
carbamychloline
pilocarpine
Methacholine is used as a provocative agent to identify
reactive airway disease in those who do not have clinically apparent signs of asthma
Methacholine evokes
bronchoconstriction
increases airway secretions
impairs peak expiratory flow rates via M3
Bethanachol is relatively selective for
M3 receptors in the GI and urinary tracts and is used to treat nonobstructive urinary retention in the perioperative period
Carbamylcholine and pilocarpine produce
miosis and have applications in treating glaucoma
What is the specificity of atropine, glycopyrrolate, and scopolamine?
little to no muscarinic subtype specificity
Low does atropine (<0.1 mg) may cause or worsen
bradycardia by blocking presynaptic M1 receptors
Muscarinic antagonist effects of atropine dose 0.5-1.0 mg:
increased HR
dry mouth
lack of sweating
feeling thirsty
pupillary dilation
Muscarinic antagonist effects of atropine dose 2-5 mg:
tachycardia
palpitations
mydriasis
cycloplegia
restlessness
confusion
Muscarinic antagonist effects of atropine dose >5 mg:
profound tachycardia
mydriasis
cycloplegia
hot flushed skin
fever hallucinations
coma
death
What should be given in the setting of atropine overdose?
physostigmine 1-2 mg IV b/c it will cross the BBB
What effect does diltiazem have on the AV node?
a. sympathomimetic
b. negative inotropic
c. positive inotropic
d. negative dromotropic
d. negative dromotropic
A dromotropic agents affects the
conduction speed in the AV node of the heart
What are the cardiac and vascular effects of calcium channel blockers?
vasodilation
negative chronotropic
negative inotropic
negative dromotropic effects
impact on baroreceptors
What are the three major classes of Ca2+ channel blockers?
dihydropyridines
benzothiazepines
phenylalkylamines
What are examples of dihydropyridines?
nifedipine
nimodipine
nicardipine
clevidipine
What are examples of benzothiazepines?
diltiazem
What are examples of phenylalkylamines?
verapamil
CCBs drugs produce __________ relaxation of arterial than venous smooth muscle
greater
Many of the CCBs induce
coronary artery vasodilation and inhibit coronary artery vasospasm
The CCBs reduce
myocardial oxygen consumption
Antiarrhythmics that depress electrical impulses in the SA and AV nodes include
verapamil and diltiazem
Calcium channel blockers are widely used to treat
hypertension
arrhythmias
PVD
cerebral vasospasm
angina
What CCBs should be used to control HR?
verapamil and diltiazem- good choices with tachycardia, atrial fibrillation, or aflutter
What CCBs should be used to control contractility?
highest to lowest that impair contractility: verapamil> nifedipine> diltiazem> nicardipine
What CCBs should be used to control vascular tone?
nifedipine and nicardipine are best used in the treatment of HTN from elevated SVR
____________ is the only CCB proven to reduce M & M from cerebral vasospasm.
Nimodipine
CCBs preserve _______ while reducing _________
preload; LV afterload
Describe Verapamil’s effect on vasodilation, chronotropy, dromotropy, and inotropy.
not a potent vasodilator
strong depressor of chronotropy, dromotropy, and inotropy
Use of verapamil in the presence of a B1 antagonists may cause
complete heart block or profound myocardial depression
What is the dosing of verapamil?
2.5-10 mg over 2 minutes
What is diltiazem’s effect on vasodilation, chronotropy, and dromotropy?
produces arteriolar vasodilation
potent negative chronotropic and dromotropic effects
Clevidipine is highly selective for
arterial smooth muscle without negative chronotropic or inotropic effects
________ may be seen with clevidipine
Reflex baroreceptor-mediated increases in HR
Nimodipine is useful in treating
cerebral vasospasm because it crosses the BBB producing cerebral arterial vasodilation
What is the effect on nifedipine on venous and arterial tone?
selective arterial vasodilator without effect on venous tone
Nifedipine is often combined with a
b1 antagonist to prevent reflex tachycardia
Nicardipine is similar to
nifedipine but has longer duration
will see baroreceptor reflex tachycardia
Which calcium channel blocker is devoid of chronotropic effects and is ideally suited for IV infusion?
clevidipine
Which type of calcium channel do CCBs target?
L-type
Which calcium channel blocker is often prescribed for Raynaud’s disease?
Nifedipine
