module 8 antiarrhythmics class 1

Question 1

cardiac action potential has 5 phases

Answer 1

0: depolarization (Na influx)
1: Na channels close, fast K efflux
2: plateau: Ca influx
3: Ca channels close, K efflux
4: repolarization

Question 2

Class 1a MOA

Answer 2

inhibit Na fast channels -> slowing of phase 0 depolarization and prolonging repolarization.

Question 3

Class 1a indications

Answer 3

ventricular ectopy
conversion of a-fib and flutter
wolfe parkinson white

Question 4

Class 1a drugs

Answer 4

procainamide
quinidine
disopyramide

Question 5

Procainamide AE

Answer 5

QT prolongation
lupus-like syndrome
rash
agranulocytosis

Question 6

quinidine AE

Answer 6

QT prolongation 
hepatitis
hemolysis
thrombocytopenia
N/V/D
inc. digoxin levels

Question 7

disopyramide AE

Answer 7

QT prolongation
anticholingeric effects
negative inotrope (do not use with HF)

Question 8

class 1b MOA

Answer 8

shorten phase 3 repolarization and dec. the duration of the AP

Question 9

class 1b drugs

Answer 9

lidocaine

mexiletine

Question 10

lidocaine

Answer 10

inpatient use, admin IV
AE: 
- seizures
- delirium
- paresthesis

Question 11

Class 1b uses

Answer 11

ventricular arrhythmias

Question 12

mexiletine

Answer 12

oral analogue of lidocaine

used for long-term tx

Question 13

class 1c MOA

Answer 13

slow phase 0 depolarization

inhibit fast Na channel, slow AV conduction

Question 14

Class 1c drugs

Answer 14

flecainide

propafenone

Question 15

Class 1c contraindication

Answer 15

structural heart disease

• valve disease
• HF
  inc. mortality

Question 16

flecanide MOA

Answer 16

inhibits fast Na channels -> slow conduction

blocks K channels -> longer AP

Question 17

flecanide uses

Answer 17

maintain SR in a-fib or flutter

treat refractory ventricular arrhythmia

Question 18

flecanide AE

Answer 18

blurred vision
dizzy
nausea

Question 19

propafanone MOA

Answer 19

slows conduction in all cardiac tissue

Question 20

propafanone AE

Answer 20

proarrhythmic effects
moderate negative inotrope
dizzy
conduction abnormalities
- can worsen HF
- can cause bronchospasm