00 Antiarrhythmics Flashcards
What are Class I antiarrhythmics main MOA?
Sodium channel blockers
What is Class I divided?
Class Ia (intermediate acting), Class Ib (short acting), Class Ic (long acting)
What are the Class Ia drugs?
Disopyramide, Quinidine, Procainamide
What are the Class Ib drugs?
Lidocaine, Tocainide, Mexiletine (Phenytoin)
What are the Class Ic drugs?
Flecainide, Propafenone, Morizicine
Which Class I subgroup has the most ADRs?
Class Ia
What are some of the ADRs seen with Class Ia drugs?
Strong antiACh, All agents capable of causing QT prolongation (from blocking K channels) –> TdP, all proarrhythmic
Which Class Ia has the most DDIs and can cause Cinchonism?
Quinidine
What are Class Ib drugs only useful for?
VENTRICULAR arrhythmias (can’t be used for A.fib)
What kind of ADR is seen with Class Ib drugs?
All cross BBB d/t lipophilicity, all have CNS depression ADRs
When do you NOT want to use Class Ic drugs?
Do not use in patients with ischemic (CAD) or structural heart disease (LVEF < 40% or severe LVH). Avoid in heart disease!
Which Class I subgroup has the least ADRs?
Class Ic
What are the Class II Antiarrhythmics?
Beta-Blockers (Metoprolol, Propranolol, Esmolol)
What are the Class II Antiarrhythmics mainly used for?
Ventricular rate control and to prevent ventricular arrhythmias
What is unique about Esmolol (Class II Antiarrhythmics)?
Ultra short acting, IV only, large fluid volume (comes in big IV bag)
How do Class III Antiarrhythmics work?
Prolong refractory period. Blockade of potassium channels
What are the Class III Antiarrhythmic drugs?
Amiodarone/Dronedarone. Sotalol. Ibutilide/Dofetilide
How is Ibutilide different than the other Antiarrhythmics in Class III?
Instead of blocking potassium channels, it activates inward sodium channels
What are the Class IV Antiarrhythmic drugs?
CCBs (Verapamil and Diltiazem)
What are Class IV Antiarrhythmic drugs used for?
Slow conduction through AV node, used for ventricular rate control
What are the common ADRs with Verapamil?
Constipation/GERD
What are some common Antiarrhythmics used that don’t fall into the four classes?
Adenosine. Digoxin. Magnesium
What is Magnesium most commonly used for?
Torsades de Pointes
What is the DOC for patients with ischemic (CAD) or structural heart disease (LVEF < 40% or severe LVH)?
Amiodarone
What is the PK of Amiodarone like?
Slow distribution (need loading dose). Long half-life (60 days parent compound, up to 180 days for desethylamiodarone)
What is the PO dosing for Amiodarone like?
LD: 800-1600 mg/day
Maintenance: 100-400 mg/day
What is the IV dosing for Amiodarone like?
150mg x1, 1mg/min x6h, 0.5mg/min x18h = approx 1g in first day. For life-threatening arrhythmias (ACLS): 300mg IV push
What are the most common ADRs with Amiodarone?
Thyroid (hypo/hyper), Pulmonary fibrosis (dose and time dependent, treatment limiting step), Hepatic, GI (take with food), Photosensitivity
What looking at AF management, what must you think about?
Always consider the need for the 3 major therapeutic modalities: Ventricular rate control, Anticoagulation, Rhythm conversion/maintenance
What type of agents can be selected for Ventricular Rate Control in AF?
Class II and IV (Beta-blocker, CCB (Diltiazem, Verapamil)), Digoxin, Amiodarone (less common)
What are the factors looked at for the CHADS2 score?
CHF (1), HTN (1), Age 75+ (1), Diabetes (1), Stroke/TIA (2)
How does the CHADS2 score determine anticoagulation needs?
0 = ASA, 1 = ASA or Warfarin/Dabigratran/Rivaroxaban/Apixaban, 2+ = Warfarin/Dabigratran/Rivaroxaban/Apixaban
What agents are used for Rhythm CONVERSION?
1a, 1c, III. (II & IV are rate control). Amiodarone DOC for patients with ischemic or structural heart disease (Dronedarone may be first-line for all others). Sotalol DOC for post-MI/CAD w/o structural heart disease
What must be monitored when initiating Amiodarone?
Liver function and Pulmonary function
What properties does Propafenone have?
Beta-blocker
Which agent must be initiated in-hospital with renal function and QT documented?
Dofetilide
Make sure you know:
The chart on slide 57
