Table of Contents
Anti-arrhythmic drugs
Anti-arrhythmic drugs are those which are utilized for the treatment of arrhythmia. In the realm of cardiovascular health, maintaining a regular heartbeat is crucial. However, for individuals suffering from arrhythmias, or irregular heart rhythms, this can be a significant challenge.
Definition of arrhythmia
Arrhythmia refers to an abnormal heart rhythm, which can be either too fast or too slow. It occurs when electric impulse in the heart don’t work properly. It is also known as cardiac arrhythmia. A normal heart rate of any heart is 72bpm, if any case it decreases 60 beats per minute then it is called Bradycardia and if any case it increases more than 100 beats per minute then it is called Tachycardia.
Anti-arrhythmic drugs are used in the maintain of heart rate, they can help in the manage of normal heartbeat. These drugs are prescribed by healthcare professionals after complete checkup of patients. This type of drugs works properly by influencing the electrical impulse the control the heart contractions.
Symptoms of arrythmia
Chest pain
Fluttering in chest
Dizziness
Palpitation
Shortness of breath weakness
Reasons of arrythmia
Coronary artery disease
Heart valve disease
Heart failure
Cardiomyopathy
Electrolyte imbalance
High blood pressure
Certain medications and drugs
Classification of Anti-arrhythmic drugs
1. Class- I
This drug is properly work by blocking sodium channels in the heart cells, because of this reduce the electrical conduction and anxiety of the heart tissue. It is also known as a sodium channel blockers and membrane stabilizing agent. Drugs is this class is interfered with sodium channel and inhibit the influx of sodium.
Now due to inhibition of sodium channel, concentration of sodium ions is decreases inside the cell which causes relaxation(repolarization). These drugs decrease the depolarization of phase-0, which give time to our heart to relax or normalize.
These drugs further divided into three subparts:
Class- IA
These drugs block open state sodium channel, this block delayed channel recovery time from 1-10 second. Due to this, these drugs decrease conduction & increases refractory periods. Examples of Class 1A anti-arrhythmic drugs include: Quinidine, Procainamide and Disopyramide. This drug is used in the treat of ventricular arrhythmia and prevent atrial fibrillation.
Class- IB
These drugs block inactivated state sodium channel but not delay channel recovery time. This drug works for very short time and no delay in action potential (conduction). Examples of Class 1B anti-arrhythmic drugs include: lidocaine & phenytoin. It is basically used in the decrease the automaticity and triggered activity, also used as local anesthesia.
Class- IC
These drugs are most potent sodium channel blockers. These drugs have longest channel recovery time (more than 10sec). Examples of Class 1C anti-arrhythmic drugs include: Propafenone & flecainide. This drug is used in the treat atrial fibrillation and tachycardia.
2. Class- II
Class- II drugs, also known as beta blockers, target the adrenergic receptors of the heart. These drugs given their action by blocking B1 receptor in sympathetic system, which further decreases the sympathetic nervous system results decrease in heart condition, which causes relaxation and suppress ectopic activity. Examples of Class-II anti-arrhythmic drugs include: Propranolol, Esmolol and Atenolol. This is usually oral administration but for rapid through infection.
Uses of Class-II anti-arrhythmic drugs
It is used in sinus tachycardia.
It is also used to treat some other heart diseases such as CHF and hypertension.
3. Class-III
It is also known as potassium channel blockers. These are those agents which blocks the potassium channels, which are inhibit the outflow of potassium ion. Due to this, phase III (repolarization) is prolonged and overall prolong the duration of action potential. This helps in stabilizing the heart’s electrical activity. Some drugs of class III have also a beta blocker activity. Examples of Class-III anti-arrhythmic drugs include: Amiodarone, sotalol, beryllium and etc.
Uses of Class-III anti-arrhythmic drugs
It is used to treat ventricular tachycardia and atrial fibrillation.
It is also used to treat re-entry & atrial flutter.
4. Class-IV
These are non-dihydropyridine calcium channel blockers, reduce the entry of calcium into the heart cells, leading to a slower heart rate and less forceful contraction. These drugs block l-type voltage sensitive calcium channel. Now due to this, inhibit calcium ion influx which is responsible for contraction. These major effects of these drugs are in vascular smooth muscle and heart. Verapamil and diltiazem are examples of Class-IV anti-arrhythmic medications.
Uses of Class-IV anti-arrhythmic drugs
It is useful in treating re-entrant supraventricular tachycardia.
It is also useful in reducing the ventricular rate in atrial flutter and fibrillation.