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Saturday 10 May 2014

Quick Review Anti arrhythmic



Initial division on bases of which Receptor they block

Class 1: Sodium blocker
Class 2: Beta blocker e.g. Esmolol
Class 3: Potassium blocker e.g. AIDS (Amiodarone, Ibufitilide, Dofetilide, Sotalol)
Class 4: Calcium Channel blocker e.g. verampil

Class 1 is further divided on bases of action potential

Class 1A: prolongs Action potential (procainamide, qunidine)
Class 1B: decreases Action potential (lidocaine)
Class IC: no action (flecainide, NOT USED ANY MORE so DUHS ask it by asking which drug is obslete cause it increases risk of arrhythmia!! Oh Irony)

Specific Actions:

1A: activated Sodium channel
1B: Ischemic heart attack (Fav question which anti-arrhythmic after MI? answer: Class IB or lidocaine)

In Which Phase they act

Class 1: Phase O of slow fibres
Class 2: Phase 4 of fast fibres
Class 3: Phase 3 o f slow fibres
Class 4: Phase 0 of fast fibres

Specific Side affects:

Prolongs QT interval (torsade de points): Class IA and Class III
Dont use in Asthma, COPD, diabetes: Class II (beta blocker)
Causes SLE: Procainamide
Cinchonism: Quinidine
Pulmonary fibrosis, hepatotoxic, hypothyrodism, corneal deposit: Amidorine

Which Drug to use When?
After MI: Lidocaine
SVT: Adenosine (blocks all channel)
Torsade de points treatment: Mg
To control rate: Beta blocker
Preventation of SVT: Calcium channel blocker
Wolf Parkinson: Class IA

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