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| Antiarrhythmic drugs |
What is the definition of Antiarrhythmic
Antiarrhythmic are the drugs that are used in treatment and prevention of
arrhythmic condition like cardiac arrhythmias,ventricular fibrillation,atrial
fibrillation,atrial flutter.it is also known as cardiac dysrhythmia
medications.
Antiarrhythmic drugs develop by a pharmacological tutor
Miles Vaughan Williams in 1970 so it is also called
Vaughan Williams Classification
Arrhythmia :- Arrhythmia is an abnormality of the rate rhythm side of
origin of cardiac impulse or an abnormality in the impulse conduction.
OR
Arrhythmia is an medical condition of irregular heart beat and show various
condition like tachycardia,bradycardia.
Mnemonic (Trick) for remembering Antiarrhythmic Drugs Classification
The mnemonics which helpful in the remembering antiarrhythmic drugs classification is "sotalol is potassium channel blocker" in which Sotalol - S means sodium channel blocker ,Potassium - P means potassium channel blocker ,Channel - C means calcium channel blocker , Blocker - B means beta adrenergic blocker.and the mnemonics for remembering drugs is given below in every class of drug.
Classification and list of Antiarrhythmic drugs
According to Miles Vaughan Williams the antiarrhythmic drugs
are classified in mainly four classes these are.........
(A) Class - 1 :-
Sodium Channel Blocker
(1) Prolonged Repolarization
- Quinidine
- Procainamide
- Disoyramide
- Moricizine
Mnemonics ( Tricks ) :- Dimpple is the Queen of MP
(2) Shorten Repolarization
- Lignocain
- Mexiletine
(3) Little effect on Repolarization
- Flecainide
- Encainide
- Propafenone
(B) Class - 2
Beta adrenergic bloker
- Acebutolol
- Propranolol
- Esmolol
- Sotalol
(C) Class - 3
Potassium Channel Blocker
- Ibutilide
- Amiodarone
- Bretylium
(C) Class - 4
Calcium Channel Blocker
- Verpamil
- Diltiazen
Sodium Channel Blocker (Class -1 Antiarrhythmic drug)
Class - 1 Antiarrhythmic drug are also known as membrane-stabilizing
agents.the primary action of these class drug is to limit the conduction of
sodium across cell membrane - a local anesthetic action.they also reduce rate
of phase 4 depolarization in automatic cell.it is divided in three groups.....
- Prolonged Repolarization (Class IA)
- Shorten Repolarization (Class IB)
- Littel effect on Repolarization (Class IC)
Quinidine :-
Quinidine is the dextroisomer of the antimalarial alkaloid quinine found in
"cinchona bark".
Quinidine is an medication that act as class - 1 antiarrhythmic agent in the
heart.the drug cause increase action potential duration.
The brand name of of quinidine is Nuedexta that is used to treat
irregular heart beat called arrhythmia and it is also used in the treatment of
uncomplicated malaria.
It metabolize 95 % in liver and plasma half life is an half hour.
Beta Adrenergic blocker (Class - 2 Antiarrhythmic drugs)
The most commonly selected beta blocker for treatment and prevention of
cardiac arrhythmias is propranolol that suppress the adrenergic mediated
ectopic activity.these class of drugs are particularly useful in the treatment
of supraventricular tachycardias.these class of drug are contraindicated in
the patient who are suffer from asthma.
Pottasium Channel Blocker (Class - 3 Antiarrhythmic drug)
The characteristics action of this class is prolon-gation of repolarization
.AP is widened and ERP is increased.The tissue remains refractory even after
full repolarization. The potassium channel blockers include in classification of antihypertensive drugs also.
Amiodarone :- It is the powerful antiarrhythmic drug used to treat and
prevent of irregular heart beat
The pharmacokinetics of these drug is onset of action is slow may very from
2-3 days to several weeks,duration of action and plasma half life time may
from weeks to months and it metabolize in the liver.
Dose :- Amiodarone is mainly be use orally 400-600 mg/day orally
and 100 to 800 mg slow IV(5mg/kg).
Calcium Channel Blocker (Class - 4 Antiarrhythmic druG)
The primary action of class - 3 is is to inhibit calcium mediated slow channel
inward current.these class of drug act by depress calcium depended action
potentials in slow channel tissue.these drug are primarily used for the
treatment of supraventricular tachycardia.they have less of an effect on sinus node activity.
Mechanism of action of Antiarrhythmic drug)/How it works ?
The mechanism of action of antiarrhythmic drug are different according to
there class ...........
(A) Mechanism of action of Class - 1 Antiarrhythmic drugs
It act by blocking sodium channel,it depresses all cardiac properties like
automaticity,excitiblity and conduction.
Prolagtion of action potential duration is due to potassium channel block
while lengthening of effective refractory period is caused by its moderate
effect on recovery of sodium and potassium channel.
(B) Mechanism of action of Class - 2 Antiarrhythmic drugs
The class of antiarrhythmic drug are act on adrenergic receptor by blocking
the action of adrenergic receptor results in decrease norepinephrine leads in
vasodilation and increase blood flow.
(C) Mechanism of action of Class - 3 Antiarrhythmic drugs
Class - 3 antiarrhythmic drug act by blocking the potassium channel and
prolong the action potential duration duration in arterial and ventricular
muscles.
It also blocks the sodium and calcium channel and depress S.A node pacemaker
activity.
(D) Mechanism of action of Class - 4 Antiarrhythmic drugs
Class - 4 antiarrhythmic drug act by block voltage depend calcium channel and
decrease impulse conduction to A.V node ,thus preticting the ventricles from
atrial tachyarrhythmia.
What are the uses of Antiarrhythmic drugs ?
The use of antiarrhythmic drug are following according to class of
drugs...............
(A) Uses of Class - 1 Antiarrhythmic drug
- Cardiac Arrhythmia
- Epilepsy
- Chronic pain
- Atrial flutter
- Atrial fibrillation
- Wolf-Parkinson-Syndrome
(B) Uses of Class - 2 Antiarrhythmic drugs
- Cardiac Arrhythmia
- Hypertension
- Angina Pectoris
- Supraventricular Tachycardias
- Atrial flutter
- Atrial fibrillation
- Sinus Tachycardia
(C) Uses of Class - 3 Antiarrhythmic drugs
- Severe Ventricular Tachycardia
- Atrial Failure
- Angina Pectoris
- Atrial Fibrillation
(D) Uses of Class - 4 Antiarrhythmic drugs
- Arrhythmia
- Hypertension
- Angina Pectoris
- Migraine
What are the most common side effect of Antiarrhythmic drugs ?
(A) Side effect of Class - 1 Antiarrhythmic drugs
- Nausea
- Vomiting
- Diarrhoea
- Lightheadedness
- Skin Rash
- Heart Burn
- Stomach Pain
- Blurred Vision
- Stomach Pain
- Dizziness
- Yellowish of Skin
(B) Side effect of Class - 2 Antiarrhythmic drugs
- Vomiting
- Nausea
- Bradycardia
- Cold fingers
- Drowsiness
- Headache
- Bradycardia
- Dizziness
- Congestive heart failure
(C) Side effect of Class - 3 Antiarrhythmic drugs
- Vomiting
- Nausea
- Anorexia
- Diarrhoea
- Hepatotoxicity
- Headache
- Hypertension
- Flushing
- sensitivity of skin to sunlight
(D) Side effect of Class - 4 Antiarrhythmic drugs
- Dry mouth
- Headache
- Edema
- Dizziness
- Constipation
- Flushing
What are drug of choice and best drug for antiarrhythmic drug ?
The drug of choice and best drug for antiarrhythmic drug is amiodarone
it is powerful medicine which helpful in treat irregular heart beat by
blocking the electrical signal in heart which cause irregular heart beat.
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