11. Anti Arrhythmic Drugs Class 1 (a,b &c) Flashcards by Julie Amos

Based on Vaughan-Williams Classification, what are the 4 classes?

Type 1 - sodium channel blockers 
1a intermediate t(recovery)
1b short t(recovery)
1c long t(recovery) 
Type II - beta antagonists 
Type III - drugs that prolong action potential 
Type IV - calcium channel blockers

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What are the 3 type 1a drugs?

Quinidine, procainamide and disopyramide

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What are the main effects of type 1a?

Decreases conduction velocity of bundle of his, perkinje fibers, and ventricles
Prolongs refractory period
Decreases automaticity of Na - makes threshold more positive
Block potassium channels

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What are the effects of quinidine?

Blocks Na channels, K channel and Ca channel
Antimuscurinic properties - speed conduction through AV node
Blocks alpha-1 –> vasodilation

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How is quinidine administered usually? What the IV administration for?

Administered PO

IV administration for atrial or ventricular tachycardia

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What is the black box warning for quinidine?

PO: increase mortality in nonlife threatening arrhythmia vs. other AADs; proarrhythmic - QTc prolongation and TdP possible

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What are the adverse effects of quinidine? What are toxicity symptoms? What should be monitored?

TdP, GI upset, immune rxn
Head ache, dizziness, tinnitus
EKG, CBC, LFTs

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How is procainamide administered?

IV or IM

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What is the black box warning for procainamide?

watch for systemic lupus erythematosus and bone marrow depression

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What is the main indication for procainamide?

Use for life threatening ventricular arrhythmias only

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Does procainamide under go renal metabolism? Hepatic metabolism?

yes and yes

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What are the contraindications of procainamide?

SLE, heart block, history of TdP

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What should be monitored with procainamide?

EKG, BP, antinuclear antibody (ANA), CBC

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What is the usage for disopyramide?

For use in life threatening ventricular arrhythmias only

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What is the black box warning for disopyramide?

Can precipitate CHF in pts w/ left ventricular dysfunction

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Does disopyramide undergo hepatic and/or renal metabolism?

Yes and yes

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What are the contraindications of disopyramide?

Cardiogenic shock, QTc prolongation

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What are the adverse effects of disopyramide?

Anticholinergic effects, TdP, CHF, hypotension, anorexia

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What should be monitored with disopyramide?

EKG, BUN/sCr, LFTs, blood glucose

What is the Vaughan-Williams Classification of Antiarrrhythmic Drugs?

Categorizing drugs according to their electro physiological effects on their heart (rather than therapeutic target)

What are the three type 1b Antiarrhythmic drugs?

Lidocaine, mexilitine, to asinine, phenytoin

What are the effects of class 1b antiarrhythmic drugs?

effect tissue w/ frequent rate of depolarization
decrease automaticity of Na dependent conductive tissues (ex ectopic pacemakers)
decrease AP duration
no effect on conduction velocity, but decreases the frequency of firing
used to terminate arrhythmias that are caused by ectopic pacemakers

What is the primary use of class 1b AADs?

Primarily used to terminate arrhythmias that are caused by ectopic pacemakers

What is the primary use for lidocaine?

Used for ventricular arrhythmias in ACLS

Treatment of choice in acute ischemic ventricular arrhythmias

What is the contraindications of lidocaine?

3rd degree heart block, don't want to loose communication between atria and ventricles

What are some adverse effect of lidocaine?

Tremor, nausea, slurred speech, seizures

How is mexilitine similar to lidocaine?

It's an oral lidocaine derivative

What is the black box warning for mexilitine?

Should only be used to treat life threatening ventricular arrhythmias due to its pro-arrhythmic effect

What are some adverse effects of phenytoin?

CNS effects, GI symptoms, gingival hyperplasia, hair growth, hypersensitivity

What are contraindications of phenytoin?

Sinus bradycardia | AV block -- phenytoin will worsen AV node block

What will barbiturates do to phenytoin metabolism?

Barbs will induce phenytoin metabolism by inducing CYP450 expression, will want to increase phenytoin dose

What are 3 type 1c AADs?

Flecainide, propafenone, moricizine

What are the effects of class 1c AADs?

- Slowing of conduction velocity | - Has no effect on automaticity of ectopic pacemakers

What are the effect of flecainide?

- decreased conduction velocity - blocks K channels - blocks Ca channels

What is flecainide used to treat?

Atrial and ventricular arrhythmias conversion and maintenance of NSR

What is the black box warning for flecainide?

Do not use with post-MI or LVDF | pts, may increase mortality

What are the contraindications of flecainide?

2nd and 3rd degree heart block, or LVDF

What are some adverse effects of flecainide?

Vtach, double vision, HF, dyspnea

What are the effects of propafenone?

- decrease conduction velocity - block K channels - block b-AR receptors: depresses triggered activity (DAD, EAD) decreases heart rate

What is the main use of propafenone?

Mainly used IV and PO for atrial arrhythmia conversion and maintenance of NSR

What are the adverse effects of propafenone? What are they mainly caused by?

Mainly caused by b-AR blockage - exacerbate HF - bronchospasms - sinus bradycardia

What is the black box warning with propafenone?

Only for life threatening arrhythmias, has a significant pro-arrhythmic effect

What are some things that should be monitored while on propafenone?

EKG - watching for QTc prolongation LFTS, CCB, electrolytes All should be measured every 6 months

What is the CAST trial?

Compared pts with ischemia and potential for SCD due to ventricular arrhythmias on either 1c AADs or placebo

What was the findings of the CAST trial?

Do not give 1c AADs to individuals post-MI or with LVH