CVS - Antiarrhythmic Drugs Flashcards
Depolarization is due to opening of which channels
Na+ channels
Repolarization and Hyperpolarization is due to opening of which channels
K+ channels
Phases of Action potential of Heart
Phase 0 - Depolarization (due to opening of Na+ channels)
Phase 1 - Repolarization (due to opening of K+ channels)
Phase 2 - Plateau phase (Both K+ And Ca2+ channels open)
Phase 3 - Only Potassium channel remains open
Effect on AP graph after giving Na+ channel blockers
Decrease slope of Phase 0
Effect on graph of AP after giving K+ channel blockers
Increase in APD (Action potential duration)
Effect on graph of AP after giving K+ channel openers
Decreases APD
Effect of K+ channel blockers on QT interval
Increases
Classification of Antiarrhythmic drugs
Vaughan Williams Classification
Class i - Na+ Channel blockers
Class ii - Beta Blockers
Class iii - K+ Channel blockers
Class iv - CCB
Class v - Others
Class i drugs can be classified into
Class ia - Na+ Blockers + K+ blockers
Class ib - Na+ blockers + K opener
Class ic - Na blockers, No effect on Potassium
Effect of Class i drugs on AP
Slope of Phase 0 decreases
In ia - APD increases
In ib - APD decreases
In ic - No change in APD
Class ia drugs
Quinidine
Procainamide
Class ib drugs
Lignocaine
Phenytoin
Tocainide
Class ic drugs
Encainide
Flecainide
Propafenone
Class ii drugs or beta blockers can be used in which arrythmias
Atrial or ventricular tachyarrythmias
Class iii or K+ channel blockers
B - Bretylium
I - Ibutilide
N -
D - Dofetilide
A - Amiodarone
S - Sotalol
Bretylium uses
Was user for ventricular fibrillation earlier
Known as Pharmacological defibrillator
Ibutilide and Dofetilide can be used in
Atrial fibrillation
Which drug is Beta blocker and also blocks K+ channel
Sotalol
Which is longest acting antiarrhythmic drug
Amiodarone - half life more than 3 weeks
Amiodarone uses
Commonly used to prevent Arrythmias
Used as loading dose for acute arrythmia
Can be used for all arrythmias except QT prolongation
Which antiarrhythmic drug have all 4 mechanism of action
Amiodarone
Side effects of Amiodarone
The - can increase or decrease Thyroid
Peripheral of - Peripheral neuropathy
My - Myocardial depression
Lung - Lung fibrosis
Liver and - Hepatotoxic
Cornea is - Corneal deposits
Photosensitive - Photosensitivity (Blue man Syndrome)
Drugs which can cause Pulmonary fibrosis
Bleomycin
Amiodarone
Methotrexate
Cyclophosphamide
Busulfan
Class iv drugs or Calcium channel blockers
Verapamil - used in tachyarrythmias
Diltiazem
DHPs - not preferred in heart
