Anti-arrhythmic
These are drugs used to prevent or treat irregularities of cardiac rhythm.
Symptoms
A fluttering in your chest
Anxiety.
Fatigue.
Sweating.
dizziness
Palpitation
Palpitation
CLASSIFICATION
[CLASS-1] : Na+ channel blocker [agents interfere with the sodium (Na+) channel]
A.Minimal phase 'O' depressors [shorten repolarization]
Lidocaine
Phenytoin
Mexiletine
Tocainide
B.Moderate phase 'O' depressors [prolong repoarization]
Quinidine
procainamide
disopyramide
moricizine
C. Marked phase 'O' depressors [No effect on repolarization]
Encainide
Flecainide
idecainide
lorcainide
[CLASS-2] : 𝛃-adrenoreceptor blocker [agents are anti-sympathetic nervous system agents]
propranolol
acebutolol
Esmolol
[CLASS-3] : K+ channel blocker [agents affect potassium (K+) efflux]
Amiodarone
Bretylium
sotalol
[CLASS-4] : Ca++ channel blockers [agents affect calcium channels and the AV node]
Verapamil
Diltiazem
MECHANISM OF ACTION
[CLASS-1] : Na+ channel blocker [agents interfere with the sodium (Na+) channel] :
Class-1(A):
(Na+) channel block (intermediate association/dissociation) and K+ channel blocking effect; affects QRS complex
MECHANISM OF ACTION
Class-1(A):
(Na+) channel block (intermediate association/dissociation) and K+ channel blocking effect; affects QRS complex
Class-1A prolong the action potential and has intermediate effect on the 0 phase of depolarization
Class-1(B):
Na+ channel block (fast association/dissociation); can prolong QRS complex in overdose
class 1b shorten the action potential of myocardial cell and has weak effect on intiation of phase 0 of depolarization
Class-1(C):
Na+ channel block (slow association/dissociation) has no effect on action potential and has the strongest effect on the initiation phase 0 of depolarization
DOSE:
* Lidocaine: given only by
iv route: 50-100 mg bolus followed by 20-40 mg every
10 20 min or 1-3 mg/min infusion.
* Quinidine: PRONESTYL 250 mg tab., I g/10 ml inj.
* Propafenone: 150 mg BD- 300 mg TDS
ADVERSE EFFECTS:
1(A) Lidocaine: CNS effects
2(B) Quinidine: cinchonism
3(C) Flecainide: Blurred vision, nausea
[CLASS-2] : 𝛃-adrenoreceptor blocker
Their mechanism in Arrhythmia is primarily cardiac beta blockage and reduction in cAMP,which resulting in both sodium and calcium currents and the suppression of abnormal Pacemakers.
DOSE:
* Esmolol: MINIBLOCK 100 mg/10 ml, Short acting, Route-iv.
* Propranolol: 40-80 mg 2-4
times a day.
[CLASS-3] : K+ channel blocker
They cause prolongation of the action potential duration by blockage of potassium channel that are responsible for the repolarization of the action potential.
AP prolongation result in effective refractory period and reduce the ability of the heart to respond to rapid ectropic beat
DOSE:
* Amiodarone: orally 400-600 mg/day for
few weeks
* Sotalol: SOTALAR-40 mg tab, SOTAGARD-40. 80 mg tabs.
ADVERSE EFFECTS:
Fall in BP,
bradycardia and myocardial depression occurs
on i.v. injection.
Nausea, gastrointestinal upset may attend oral
medication
[CLASS-4] : Ca++ channel blockers
Cardiac effect:
* Verapamil blocks both activated and inactivated L-type calcium channel.
-AV node conduction time and effective refractory period are prolonged.
-Slow the SA node by its direct action.
DOSE:
* Verapamil: 60 to 120 mg TDS
CALAPTIN 40, 80 mg tab; 120, 240 mg SR tab, 5 mg/2 ml inj.
*Diltiazem: The direct cardiac actions of diltiazem are similar to those of verapamil
For rapid control of ventricular rate in AF or
AFI, i. v. diltiazem is preferred over verapamil,
because it can be more easily titrated to the
target heart rate, causes less hypotension or myocardial depression and can be used even
in the presence of mild-to-moderate CHF.
DOSE:
DILZEM 30, 60. 90 mg tabs, 25 mg/5 ml inj.