Anti-Arrhythmic Drugs Flashcards
Class 1a
Quinidine
Weak Na channel blocker
Class 1b
Lidocaine
Weak Na channel blocker - Reduce phase 0 conduction in ischaemic tissue
Class 1c - main ADR?
Flecainide
Strong Na channel blocker - ^refractory period in depolarising atrial tissue
Sudden death or Flecanide flutter (use w/ AV node blocker)
Class II
Bisoprolol, Propanolol, Metoprolol
B-adrenoreceptor blockers
Slows conduction at AV node - ^refractory period in AV node
Class III - main contraindication?
Amiodarone
Block K+ channels - ^refractory period
Contraindicated in thyroid disease (iodine content)
Class IV
Verapamil, Diltiazem
Ca channels blocker
Blocks Ca channels at AV node - ^refractory period in AV node
Adenosine - main ADR?
Class V
Binds to A1 receptors at AV node
Blocks adenylyl cyclase
Reduced cAMP
Activates K channels - hyperpolarisation
SENSE OF IMPENDING DOOM - brief asystole
Ivabradine
Blocks funny current in SA node
Slows sinus node firing
DOESN’T REDUCE BP
Digoxin
Best for AF in HF
As an anti-arrhythmic:
Enhances vagal activity - Slows conduction
Use in HF:
1. Blocks Na/K ATPase
2. ^Na in cell
3. Reduced activity of Na/Ca exchanger
4. ^Ca in cell
5. ^Force of contraction
Positive inotropic and Negative chronotropic drug
Atropine
Selective muscuranic antagonist
Blocks vagal activity to speed AV conduction & ^HR
Best drug for AF?
Bisoprolol
Verapamil
Best drug for WPW?
Flecainide
Best drug for sinus tachycardia?
Ivabradine (no drop in BP)
Can flecainide be used alone in AF?
No - give AV nodal blocking drugs with it (B blocker or Ca channel blocker)
Why can’t you use Ca channel blockers and B blockers together?
Both AV nodal blockers - ^risk of heart block
