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Flashcards in Antiarrhythmics Deck (38)
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1

What is a general class side effect to be aware of?

- several different effects on AP generation and propagation --> may affect autonomic NS**

2

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

3

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

Other: digoxin

4

What drugs are in Class I?

Modulate or block Na+ channels

Ia: quinidine, procainamide, disopyramide

Ib: lidocaine, mexiletine

Ic: flecainide, propafenone

5

What drugs are in Class II?

Inhibit sympathetic activity

B-blockers

6

What drugs are in Class III?

Block K+ channels

- sotalol
- dofetilide
- ibutilide
- amiodarone
- dronedarone

7

What drugs are in Class IV?

Block Ca2+ channels

- verapamil
- diltiazem

8

What are "class" interactions?

- careful w/other QT prolongers
- most metabolized by 3A4 or 2D6
- drugs causing hypokalemia or hypomagnesemia (loop diuretics) INC risk

9

What are "class" ADRs?

**Dysrhythmia**

- QT prolongation / proarrhythmic potential
- careful with brady and heart blocks

10

What is Quinidine syncope?

Recurrent lightheadedness and fainting secondary to self-terminating TdP

[drug] usually normal or even subtherapeutic

11

What is cinchonism and which drug is it related to with high concentrations?

Quinidine

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)

12

What are two ADRs of procainamide?

1. Reversible lupus-like syndrome**

2. potentially severe bone marrow suppression

13

What ADRs are related to disopyramide?

Anticholinergic, esp urinary retention
- careful w/glaucoma and BPH

14

What ADRs are related to Mexiletine?

CNS tox
- dizzy, lightheaded, unsteady gait
- tremor

15

What ADRs are related to Lidocaine?

CNS tox
- tremor MC
- seizure possible

16

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 **

17

What ADRs are related to Propafenone?

- dysguesia (altered taste)
- lupus-like reaction

** BBW - need echo to ensure structurally normal heart **

18

Sotalol interactions?

Avoid concurrent B-blockers and CCBs

Has some b-blocking activity (same precautions)

19

What is ibutilide main ADR?

proarrhythmic activity

20

What is Dofetilide main ADR?

** dysrhythmia is problematic - death possible **

start med in hospital

21

What are two specifics related to Amiodarone chemistry?

- Iodine containing compound (like thyroxine)

- highly lipid soluble and very long half life (55 days)

22

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

23

Describe the Pk Interactions of Amio?

3A4 substrate
** inhibits multiple isoenzymes moderately**

Pgp substrate & inhibitor
- may INC [digoxin] for up to 3 mo

24

Describe the Pd interactions of Amio?

- additive QTc drugs
- additive AV block/bradycardia
- drugs that induce INC K or Mg

25

** 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)

26

What are the ADRs of Amio?

1. Pulm
- IPF --> ARDs (interstitial infiltrates on imaging)

2. Thyroid (hypo)

3. Ocular
- corneal microdeposits
- optic neuropathy/neuritis

4. Derm
- photosensitivity
- bluish skin discoloration

5. CNS
- gait, ataxia, dizzy, memory, peripheral neuropathy

6. Cardiac
- brady, AV nodal block

27

How does Dronedarone compare and contrast to Amiodarone?

Some MOA but
- **non-iodinated analog**
- shorter half life and less tissue accumulation

Clinical:
- AF, a flutter [less effective at maintaining NSR compared to amio]

28

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
4. SSS
5. Brady pt

29

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**

30

What ADRs are related to Dronedarone?

Initial
- NVD
- photosensitivity (not blue though)

Emerging
- acute liver, renal failure, exacerbation of HF