Flashcards in Antiarrhythmics Deck (38)
What is a general class side effect to be aware of?
- several different effects on AP generation and propagation --> may affect autonomic NS**
Why does TdP result? When is it most commonly seen?
TdP results from QT prolongation (d/t blockade of K current)
MC with hypokalemia, hypomagnesemia, bradycardia
What is the physio behind each Vaughan-Williams class?
I: modulate or block Na+ channels
II: inhibit sympathetic activity
III: block K+ channels
IV: block Ca2+ channels
What drugs are in Class I?
Modulate or block Na+ channels
Ia: quinidine, procainamide, disopyramide
Ib: lidocaine, mexiletine
Ic: flecainide, propafenone
What drugs are in Class II?
Inhibit sympathetic activity
What drugs are in Class III?
Block K+ channels
What drugs are in Class IV?
Block Ca2+ channels
What are "class" interactions?
- careful w/other QT prolongers
- most metabolized by 3A4 or 2D6
- drugs causing hypokalemia or hypomagnesemia (loop diuretics) INC risk
What are "class" ADRs?
- QT prolongation / proarrhythmic potential
- careful with brady and heart blocks
What is Quinidine syncope?
Recurrent lightheadedness and fainting secondary to self-terminating TdP
[drug] usually normal or even subtherapeutic
What is cinchonism and which drug is it related to with high concentrations?
Dry as a bone (urinary retention)
Red as a beet (vascular flushing)
Blind as a bat (blurred vision)
Mad as a hatter (delirium, psychosis)
Hotter than hell (anhidrosis, hot skin)
What are two ADRs of procainamide?
1. Reversible lupus-like syndrome**
2. potentially severe bone marrow suppression
What ADRs are related to disopyramide?
Anticholinergic, esp urinary retention
- careful w/glaucoma and BPH
What ADRs are related to Mexiletine?
- dizzy, lightheaded, unsteady gait
What ADRs are related to Lidocaine?
- tremor MC
- seizure possible
What ADRs are related to Flecainide?
** mostly proarrhythmic --> make sure K is normal **
BBW: do not use in pt w/h/o AMI
** need echo to ensure structurally normal heart **
What ADRs are related to Propafenone?
- dysguesia (altered taste)
- lupus-like reaction
** BBW - need echo to ensure structurally normal heart **
Avoid concurrent B-blockers and CCBs
Has some b-blocking activity (same precautions)
What is ibutilide main ADR?
What is Dofetilide main ADR?
** dysrhythmia is problematic - death possible **
start med in hospital
What are two specifics related to Amiodarone chemistry?
- Iodine containing compound (like thyroxine)
- highly lipid soluble and very long half life (55 days)
What are Amio clinical indications?
FDA: life threatening recurrent VF or hemodynamically-unstable VT (ACLS)
Common unlabeled: A-fib
- AF pharm cardioversion
- AF prophylaxis following open heart surgery
- Recurrent AF
Describe the Pk Interactions of Amio?
** inhibits multiple isoenzymes moderately**
Pgp substrate & inhibitor
- may INC [digoxin] for up to 3 mo
Describe the Pd interactions of Amio?
- additive QTc drugs
- additive AV block/bradycardia
- drugs that induce INC K or Mg
** Review all interaction alerts closely for Amio **
What are the five examples given?
1. DEC warfarin dose
2. DEC PO digoxin
3. Avoid with HCV drugs
4. Avoid macrolides, FQ, fluconazole
5. Careful w/statin (use rosuva)
What are the ADRs of Amio?
- IPF --> ARDs (interstitial infiltrates on imaging)
2. Thyroid (hypo)
- corneal microdeposits
- optic neuropathy/neuritis
- bluish skin discoloration
- gait, ataxia, dizzy, memory, peripheral neuropathy
- brady, AV nodal block
How does Dronedarone compare and contrast to Amiodarone?
Some MOA but
- **non-iodinated analog**
- shorter half life and less tissue accumulation
- AF, a flutter [less effective at maintaining NSR compared to amio]
Who is Dronedarone C.I. in?
1. HF class IV or II-III w/recent decompensation
2. Pt who cannot stay in NSR
3. 2/3 deg AV block
5. Brady pt
What are 4 drug interactions to be aware of with Dronedarone?
1. strong 3A4 substrate; moderate 3A4/2D6 inhibitor (remember Metoprolol, statins)
2. Pgp inhibitor (remember digoxin)
3. QTc prolonger
4. Elevated INR with Warfarin**