Antiarrythmic Drugs Flashcards
Class I mechanism of action
Class II mech of action
Class III mech of action
Class IV mech of action
I: Na+ channel blocker
II: B adrenoreceptor blocker
III: K+ channel blocker
IV: Ca+ channel blocker
IA:
IB:
IC:
II:
III:
IV:
Slows phase 0 depo in ventricular mf
Shortens phase 3 rep in ventri
Slows phase 0 dep
Inhibut phase 4 in SA and AV
Prolong phase 3 repolarization
Inhibit action potential in SA and AV
T or F
Most anti arrythmic drugs are pro arrythmic
True
Especially class I
Class IA names:
1-
2-
3-
Quinidine
Procainamide
Disopyramide
Class IA mode of action
Slow phase 0 and prolong AP and slow conduction
Prolong repolarization by blocking some K channels
Increase ERP
T or F
Quinidine doesn’t have alpha adrenergic blocking effect and anticholinergic
False
It has
Therapeutic uses of class IA
Atrial and ventriculat tachy
Pharmakokinetics of class IA
Rapidly absorbed after oral adm
Extensive metabolism by CYP3A4
Adverse effects:
1-
2-
3-
4-
Has atropine
Tinnitus headache blurred vision
Development of some arrythmias
SA and AV block or asystole
Class IB
Mode of action:
Names
1-
2-
3-
Shorten phase 3 repolarization
Decrease the duration of AP
1-lidocaine
2-mexiletine
3-tocainide
Lidocaine:
Therapeutic uses
Phramcokinetics
Adverse
Ventricular arrythmias
Lidocaine given IV (because of extensive 1st pass effect)
CNS toxicity
Class IC
Mode of action:
Names:
1-
2-
Markedly slow phase 0 (conduction)
Have little effect on duration of the AP
1-flecainide
2-propafenone
Flecainide:
Therapeutic uses:
Adverse effects:1—–2—–
Contraindications 1——-2—–
Ventricular arrythmias
Adverse: visual disturbances-dizziness
Contra: hypersensitivity-2nd and 3rd degree AV block
B blockers:
Mode of action:
Names:
1-
2-
3-
Diminish phase 4 depo
Depress automaticity
Prolonging AV conduction
Decr HR and contractility
Esmolol
Metoprolol
Propranolol
B blocker
Uses:
Tachy arrythmias
Atrial flutter and fib and AV nodal reentrat tachy
K+ blockers
Names:
Mode of action
Amiodarone
Sotalol
Dofetilide
Prolongation of phase 3 without altering phase 0
Prolong duration of AP and ERP
Amiodarone:
Uses:
Serious ventricular arrythmias
Taken up by tissues especially adipose
T or F
Amiodarone antiarrythmic effects compromise class I II III and IV
T
Mechanism of action:
1-
2-
3-
1-Prolongation of AP and refractoriness K+ channel blocker + partially Na+ blocker effect type Ia
2- slows cardiac automaticity and AV conduction as Ca2+ channel blocker type verapamil
3- weak b-adrenergic blocker (prolongation of AP)
Contraindication:
Therapeutic uses:
-pre-existing depressed heart function because of their negative ionotropic
-recurrent and refractory ventricular and supra-ventricular arrythmias
Adverse effects of amiodarone:
1-
2-
3-
4-
5-
6-
Gray-blue skin discoloration and photo-dermatitis
Corneal microdeposits
Pulmonary fibrosis
Hypo or hyperthyrodism
Hepatic impairment
Neurological effects
T or F
The most used antiarrythmic drug is lidocaine
False
Amiodarone
Ca2+ blockers
Mode of action
Names:
1-
2-
Decrease inward Ca2+ so it decrease phase 4 spintaneous dep (SA)
Slow conduction in Ca2+ current dep like AV
1-verapamil
2-diltiazem
Uses of class IV
Effective in treating arrythmias that must traverse Ca2+ dependent cardiac tissue
Reentrant supraventricular tachycardia and in reducing the ventricular rate in atrial flutter and fibrillation
