EXAM #1: ANTIARRHYTHMIC PHARMACOTHERAPY Flashcards
What are Class I antiarrhythmics?
Na+ Blockers
What are Class II antiarrhythmics?
Beta Blockers
What are Class III antiarrhythmics?
K+ Blockers
What are Class IV antiarrhythmics?
Ca++ Blockers
What are the class IA drugs?
Quinidine
Procainamide
Disopyramide
What are the class IB drugs?
Lidocaine
Mexiletine
What are the class IC drugs?
Flecainide
Propafenone
Generally, what do you need to remember about IB vs IC drugs antiarrhythmics?
B is Best post-MI, C is Contraindicated post-MI
Why have the class IA drugs most faded from clinical use?
- Association with INCREASED MORTALITY in atrial arrhythmia
- QT prolongation is arrhythmiogenic (Torsades)
- Induces G6PD hemolytic anemia
How was Quinidine used in clinical practice?
Both atrial and ventricular arrhythmias, esp.
- Re-entrant SVT
- VT
What was the previous use of procainamide?
2nd line in ACLS algorithm (2014) for VT/VF
What toxicity is specifically associated with procainamide?
SLE-like syndrome
What metabolite is associated with procainamide toxicity?
NAPA–polymorphisms can lead to differential toxicity
What is the specific toxicity associated disopyramide?
Heart failure
*Also, anticholingeric effects i.e. dry mouth, urinary retention, constipation…etc.
What type of local anesthetic is lidocaine?
Amide
What is lidocaine specifically indicated for?
Ventricular arrhythmias especially post-MI
Note that it has been entirely replaced by Amiodarone in 2016 ACLS guidelines
What toxicities are associated with Lidocaine?
CNS stimulation/depression
Can you take lidocaine with a hx of allergy to procaine?
Yes, procaine is an ESTER
What is Flecainide indicated for?
First line agent for atrial arrhythmias WITHOUT IHD
When is Flecainide contraindicated?
Remember, Class IC is Contraindicated in patients with structural or IHD (esp. post MI)
What are the clinical indications for Propafenone?
Class IC–same as Flecainide i.e. first line for a-fib
What adverse effects are associated with Class IC drugs?
Proarrhythmic i.e. QT prolongation and Torsades
What do you need to remember about Class I drugs and CHF?
Increased mortality of Class I (all) in CHF
What positive effect is associated B-Blocker use in arrhythmias?
Decreased mortality in ventricular arrhythmias
What receptors does Sotalol have an effect on?
K+ and Beta
What is Sotalol commonly indicated for?
A-fib WITH IHD
What are the major side effects associated with Sotalol?
1) Torsades (one of the most dangerous drugs associated with QT prolongation and drug induced Torsades)
2) Excessive Beta-blockade
So bad that you’re really supposed to start the drug in the hospital
What is Amiodarone the first line agent for?
VT/VF
Why is Amiodarone so important?
Class III but has effects in all classes; thus, it is efficacious in the treatment of almost any arrhythmia
What are the major side effects associated with Amiodarone? What do you have to do when you prescribe this drug?
1) Pulmonary fibrosis (chronic use)
2) Hepatotoxicity
3) Hypothyroidism
Thus, check PFTs, LFTs, and TFTs
4) Corneal deposits (annual fundoscopic exam)
5) Blue/grey skin deposits and photosensitivity
6) Neurologic effects–fine intention tremor
What is the half-life of Amiodarone?
2 months–related to its high Vd
What drugs do you need especially conscious of when prescribing Amiodarone?
Warfarin and digoxin
What is Dronaderone?
Amiodarone without iodine–much safer than amiodarone but not as effective
When is Dronaderone contraindicated?
CHF–increased mortality
What is Dofetilide indicated for?
A-fib (both acute and chronic)
What toxicity is associated with Dofetilide?
Torsades de Points (worse than Sotalol)
This drug has the highest incidence of Torsades of ANY drug–requires 3 day admission for monitoring
How are ventricular arrhythmias commonly treated?
ICD
What is the general treatment approach for A-fib?
1) Shock
2) Drugs
What is the difference between rhythm and rate control for a-fib?
Rhythm=
- Flecainide or Propafeneone (NO IHD) vs.
- Sotalol/ Amiodarone (IHD/CHF)
Rate= Beta-blockers, diltiazem, digoxin
