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Antiarrhythmics2

Terms in this set (34)

Class 1A Drug Names
Quinidine, Procainamide, Disopyramide
Class 1A Mechanism
Increase AP duration
Increase ERP
Increase QT interval
Class 1A Use
Both atrial and ventricular arrhythmias, especially re-entrant and ectopic SVT and VT
Class 1A Toxicity
Thrombocytopenia, torsades de pointes due to QT interval prolongation

Quinidine - Cinchonism (headache, tinnitus)
Procainamide - SLE-like Syndrome
Disopyramide - Heart failure
Class 1B Drug Names
Lidocaine, Mexiletine
Class 1B Mechanism
Decrease AP duration. Preferentially affect ischemic or depolarized Purkinje and ventricular tissue.
Class 1B Use
Acute ventricular arrhythmias (especially post-MI), digitalis-induced arrhythmias.

I*B* is BB* is *B*est post-MI
Class IB Toxicity
CNS Stimulation / depression, cardiovascular depression
Class IC Drug Names
Flecainide, Propafenone
Class IC Mechanism
Significantly prolongs ERP in AV node and accessory bypass tracts. No effect on ERP in Purkinje and ventricular tissue.

Minimal affect on AP duration
Class 1C Use
SVTs, including atrial fibrillation. Only as a last resort in refractory VT
Class 1C Toxicity
Proarrhythmic, especially post-MI

I*C* is Contraindicated in structural and ischemic heC* is *C*ontraindicated in structural and ischemic heart disease
Order of Strength for Class 1 Drugs (Phase 0 inhibition)
Hail a CAB

Class 1C - Strong
Class 1A - Intermediate
Class 1B - Weak
Class 2 Drug Names
Metoprolol, propanolol, esmolol, atenolol, timolol, carvedilol
Class 2 Mechanism
Decrease SA and AV nodal activity by decreasing cAMP and decreasing Ca2+ currents. Suppress abnormal pacemakers by decreasing slope of Phase 4

AV node is particularly sensitive - increased PR interval. Esmolol very short acting
Class 2 Use
SVT, ventricular rate control for atrial fibrillation and atrial flutter
Class 2 Toxicity
Impotence, exacerbation of COPD and asthma
Cardiovascular effects: bradycardia, AV block, HF
CNS effects: sedation, sleep alterations

May mask signs of hypoglycemia
Metoprolol Toxicity
dyslipidemia
Propanolol Toxicity
exacerbation of vasospasm in Prinzmetal angina
Class 2 Antidote
saline, atropine, glucagon
Class 3 Names
Amiodarone, Ibutilide, Dofetilide, Sotalol

Mnemonic: AIDS
Class 3 Mechanism
Increase AP duration
Increase ERP
Increase QT Interval
Class 3 Use
Atrial fibrillation, atrial flutter; ventricular tachycardia (amiodarone, sotalol)
Sotalol Toxicity
torsades de pointes, excessive B Blockade
Ibutilide Toxicity
torsades de pointes
Amiodarone Toxicity
pulmonary fibrosis, hepatotoxicity, hypothyroidism / hyperthyroidism

40% iodine by weight, acts as hapten (corneal deposits, blue/gray skin deposits resulting in photodermatitis)

neurological effects, constipation, cardiovascular effects (bradycardia heart block, HF)

Check PFTs, LFTs, and TFTs when using it
Class 4 Names
Verapamil, diltiazem
Class 4 Mechanism
Decrease conduction velocity
Increase ERP
Increase PR Interval
Class 4 Use
Prevention of nodal arrhythmias (SVT), rate control in atrial fibrillation
Class 4 Toxicity
Constipation, flushing, edema
cardiovascular effects (HF, AV block, sinus node depression)
Adenosine Mechanism
Increases K+ out of cells which hyper polarizes the cell and decreases calcium current
Adenosine Use
Drug of choice in diagnosing / abolishing SVT. Very short acting ~ 15 seconds
Adenosine Toxicity
Effects blunted by theophylline and caffeine (both are adenosine receptor antagonists).

Flushing, hypotension, chest pain, sense of impending doom, bronchospasm
Mg++ Use
effective in torsades de points and digoxin toxicity
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