ANTI-ARRHYTHMICS DRUGS - CARDIOVASCULAR DRUGS (2/7)

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 Class l Na+ Channel Blocker 

Cardiovascular drugs, ANTI-ARRHYTHMICS

Block voltage gated Na+ channel like local anesthetics..slow the rate of rise of Phase 0. 

High affinity for Active & Inactive channels..little effect on resting..decrease excitability & conduction velocity.. 

Cause Pro-Arrhthymic effects……

QT interval prolongation.

ANTI-ARRHYTHMICS drugs cardiovascular system Drugs Review points


Use- Dependance

Class l bind to open or inactivated sodium channel than are fully repolarized…show great degree of blockade during depolarizing stage 

Block the cell discharging at high frequency without interfering normal  mal one

S.E=anticholinergic side effects like dry mouth, urinary retention,constipation etc

Class lB= decrease Duration of Action Potential…rapidly interact with Na+

channel..little effect on Rate of Depolarization

Lidocaine= Class lB drug...Local Anesthetic..Shorten Phase 3 repolarization..

T.E=used in Ventrical Arrhythmia in Myocardial Infarction(M.I)…

S.E=Slurred speech, Paresthesia, Convulsion, Cradiac Arrhythmia

Mexiletine & Tocainide=Class lB drugs ...similar actions to Lidocaine…

Mexiletine used for Chronic Treatment of Ventricular Arrhythmia with previous M.I

Tocainide used for Ventricular Tachyarrhythmia…has Pulmonary toxicity

Class lC=Depress the Rate of rise of Action Potential..marked slowing of conduction…little effect on Duration of Action Potential…bind Slowly to Na+ channel

Flecainide= Class lC drug….suppress Phase 0 stroke in Perkinji & Myocardial fibres…

Automaticity reduced by increasing Threshold Potential

T.E=used for Refractive Ventricular Arrhythmia…Prevention of Paroxysmal Atrial

Fibrillation/Flutter…-Ve Inotropic aggravate CHF….Suppress Premature Contractions

S.E= t1/2 16-20hr...dizziness, headache, blurred vision

Propafenone= Broad Spectrum Anti-Arrhythmic agent

Class ll Anti-arrhythmic

β-Adrenergic Antagonists..diminish Phase 4 depolarization..Prolong AV conduction..

Decreasing Heart rate & contractility

Propranolol=prevent Arrhythmia after M.I

Metoprolol=used in Cardiac Arrhythmia

Esmolol=in Acute arrhythmia in surgery or emergency situation

Class lll Antiarrhythmic

Block K+ channel...diminish K+ in repolarization stage..Prolong Duration of Action Potential...Prolong Refractory period..

Amiodarone=AntiAnginal drug...contain Iodine(I2)...structure like Thyroxine... 

show Class I, Class ll, Class lll, ClassIV activity

T.E= used in Refractive Supraventricular & Ventricular TachyarrhythmiaS.E=t1/2 of 6week…cause Blue color skin...Photosensitivity, Hypo or

Hyperthyroidism.. Neuropathy, Muscle weakness 

Dronedarone=Benzofuran Amiodarone derivative...dont have I2...used in Atrial Fibrillation 

Sotalol=β-Blocker + Antiarrhythmic……….TWO isomer : L-Isomer & d-Isomer…. 

used in Acute M.I…..Block rapid outward K+ current, known as”Delay Rectifier”

S.E= Prolong QT interval 

Dofetilide= First line Antiarrhythmic in Patients with persistent Atrial Fibrillation & Heart Disease….risk of Pro-Arrhythmia…

Class IV Antiarrhythmic 

Block Ca++channel...decrease Phase 4 depolarization…slow conduction

Verapamil & Diltiazim=greater action on heart…-Ve Inotropic…use-dependent.. 

T.E=used in Ventricular arrhythmia, Supraventricular Tachycardia, Atrial Flutter 

Other Antiarrhythmic 

Digoxin=shorten Refractory period in Atrial & Ventricular …prolong effective Refractory period...slow conduction 

Adenosine= naturally occurring Nucleoside…extreme short duration of action 15sec….. 

DOC in Acute SupraVentricular Tachycardia…cause Flushing, Chest pain, Hypotension


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