Cardio Antiarrhythmic Drug Quiz Questions and Answers
2023 with complete solution
What do class 1 antiarrythmics affect?
Fast Na channels
What do class 2 antiarrhythmics affect?
beta blockers
What to class 3 antiarrhythmics affect?
block K channels
What do class 4 antiarrhythmics affect?
calcium channel blockers
Which drugs are class 1a?
quinidine, procainamide, disopyramide
How does class 1a work?
slow the rate of rise of the action potential and prolong its duration, thus slowing
conduction and increasing refractoriness (moderate depression of phase 0 upstroke of
the action potential)
Which drugs are class 1b?
lidocaine, mexiletine
How does class 1b work?
shorten action potential duration; they do not affect conduction or refractoriness
(minimal depression of phase 0 upstroke of the action potential)
Which drugs are class 1c?
flecainide, propafenone
How does class 1c work?
prolong rise of the action potential and slow repolarization, thus slowing conduction, but
more so than class Ia drugs (maximal depression of phase 0 upstroke of the action
potential)
Quinidine
Has potent anticholinergic properties that affect the SA and AV nodes, which can
increase the SA nodal discharge rate and AV nodal conduction
This may lead to increased ventricular rates with afib or aflutter
Addition of a beta blocker, non-dihydropyridine CCB, or digoxin protects against this
Common adverse effects are GI-related - N/V/D
Proarrhythmic - torsades
Can interact with CYP3A4 inducers or inhibitors
Procainamide
Does not have the anticholinergic activity of quinidine
Prolongs the QT interval, therefore increases risk of torsades
Adverse effects:
Development of a clinical syndrome similar to SLE - most common adverse event
N/V/D and drug fever
Disopyramide (Norpace)
Potent anticholinergic and negative inotropic effects limits uses clinically
Prolongs QT, increasing risk of torsades
, Contraindicated in patients with reduced LV EF (<40%)
Adverse events:
Precipitation of CHF
Anticholinergic effects - dry mouth, urinary retention, constipation, blurred vision
Lidocaine
Selective to ischemic tissue, and especially to active fast sodium channels in the bundle
of HIS, Purkinje fibers, and ventricular myocardium
Little effect on non-ischemic tissue, the atrial myocardium, and the automaticity of the
SA node
Primarily effective in treating ventricular dysrhythmias, especially those associated with
acute MI
Cleared by hepatic metabolism, therefore, monitor closely for signs of toxicity in patients
with liver failure
Adverse events:
CNS effects of dizziness, paresthesia, disorientation, tremor, agitation, seizures and
respiratory arrest
Mexiletine
Similar to lidocaine, but in oral form
Can be used in combination with class IA and III drugs for the treatment of refractory
ventricular dysrhythmias
Not used as a single agent
High incidence of GI side effects - N/V, limits use
Other adverse effects are neurologic, such as dizziness, confusion, ataxia, and speech
disturbances
Flecainide (Tambacor)
Slows conduction velocity in the Purkinje fibers and the AV node
May lengthen PR interval and QRS duration
Most commonly used in the treatment of afib/flutter
Indicated for use in VT, but efficacy is poor
May cause a rapid VT, resistant to resuscitation, especially in patients with CAD, LV
dysfunction, LVH or valvular disease
Therefore should be avoided in this population of patients
Adverse events:
Blurred vision, dizziness, headache, tremor, N/V
Propafenone (Rythmol)
Slows conduction velocity in the Purkinje fibers and the AV node; also has a mild
nonselective beta blocking effect
May lengthen PR interval and QRS duration, leading to conduction disturbances such
as bradycardia and heart block
Most commonly used in the treatment of afib/flutter
May cause VT similar to flecainide, so avoid use in any patient with any form of heart
disease
Adverse events:
Blurred vision, dizziness, headache, N/V, bronchospasm, and taste disturbances
(metallic taste)
Beta Blockers
2023 with complete solution
What do class 1 antiarrythmics affect?
Fast Na channels
What do class 2 antiarrhythmics affect?
beta blockers
What to class 3 antiarrhythmics affect?
block K channels
What do class 4 antiarrhythmics affect?
calcium channel blockers
Which drugs are class 1a?
quinidine, procainamide, disopyramide
How does class 1a work?
slow the rate of rise of the action potential and prolong its duration, thus slowing
conduction and increasing refractoriness (moderate depression of phase 0 upstroke of
the action potential)
Which drugs are class 1b?
lidocaine, mexiletine
How does class 1b work?
shorten action potential duration; they do not affect conduction or refractoriness
(minimal depression of phase 0 upstroke of the action potential)
Which drugs are class 1c?
flecainide, propafenone
How does class 1c work?
prolong rise of the action potential and slow repolarization, thus slowing conduction, but
more so than class Ia drugs (maximal depression of phase 0 upstroke of the action
potential)
Quinidine
Has potent anticholinergic properties that affect the SA and AV nodes, which can
increase the SA nodal discharge rate and AV nodal conduction
This may lead to increased ventricular rates with afib or aflutter
Addition of a beta blocker, non-dihydropyridine CCB, or digoxin protects against this
Common adverse effects are GI-related - N/V/D
Proarrhythmic - torsades
Can interact with CYP3A4 inducers or inhibitors
Procainamide
Does not have the anticholinergic activity of quinidine
Prolongs the QT interval, therefore increases risk of torsades
Adverse effects:
Development of a clinical syndrome similar to SLE - most common adverse event
N/V/D and drug fever
Disopyramide (Norpace)
Potent anticholinergic and negative inotropic effects limits uses clinically
Prolongs QT, increasing risk of torsades
, Contraindicated in patients with reduced LV EF (<40%)
Adverse events:
Precipitation of CHF
Anticholinergic effects - dry mouth, urinary retention, constipation, blurred vision
Lidocaine
Selective to ischemic tissue, and especially to active fast sodium channels in the bundle
of HIS, Purkinje fibers, and ventricular myocardium
Little effect on non-ischemic tissue, the atrial myocardium, and the automaticity of the
SA node
Primarily effective in treating ventricular dysrhythmias, especially those associated with
acute MI
Cleared by hepatic metabolism, therefore, monitor closely for signs of toxicity in patients
with liver failure
Adverse events:
CNS effects of dizziness, paresthesia, disorientation, tremor, agitation, seizures and
respiratory arrest
Mexiletine
Similar to lidocaine, but in oral form
Can be used in combination with class IA and III drugs for the treatment of refractory
ventricular dysrhythmias
Not used as a single agent
High incidence of GI side effects - N/V, limits use
Other adverse effects are neurologic, such as dizziness, confusion, ataxia, and speech
disturbances
Flecainide (Tambacor)
Slows conduction velocity in the Purkinje fibers and the AV node
May lengthen PR interval and QRS duration
Most commonly used in the treatment of afib/flutter
Indicated for use in VT, but efficacy is poor
May cause a rapid VT, resistant to resuscitation, especially in patients with CAD, LV
dysfunction, LVH or valvular disease
Therefore should be avoided in this population of patients
Adverse events:
Blurred vision, dizziness, headache, tremor, N/V
Propafenone (Rythmol)
Slows conduction velocity in the Purkinje fibers and the AV node; also has a mild
nonselective beta blocking effect
May lengthen PR interval and QRS duration, leading to conduction disturbances such
as bradycardia and heart block
Most commonly used in the treatment of afib/flutter
May cause VT similar to flecainide, so avoid use in any patient with any form of heart
disease
Adverse events:
Blurred vision, dizziness, headache, N/V, bronchospasm, and taste disturbances
(metallic taste)
Beta Blockers
