Anti-Arrhythmia Drugs Flashcards
How is adenosine administered?
IV bolus
What is dispoyramide used for?
prevent recurrent ventricular arrhythmias
What is the mechanism of action of class IB drugs?
rapid association and dissociation rate - prevent premature beats
What is the adverse side effect of flecainide?
may trigger ventricular arrhythmias
What is the mechanism of action of class IC drugs?
slow association and dissociation rate - depress conduction
What class is verapamil?
class IV
What is the cycle of sodium channels?
non-conducting resting state - depolarisation - conducting open state - maintained depolarisation - non-conducting inactivated state - repolarisation - resting state
What is the mechanism of action of adenosine?
activates alpha 1 adrenoceptors coupled to Gi/o - opens ACh sensitive K+/GIRK channels - hyperpolarises AV node - supresses impulse conduction
What is the mechanism of action of class III drugs?
target potassium channels - prolong AP duration - increase refractory period
How is dispoyramide administered?
oral
What is paroxysmal supraventricular tachycardia?
atrial firing rate of 140-250 bpm, caused by re-entry
How is procainamide administered?
IV
What class are propranolol and atenolol?
class II
What might a high dose of verapamil cause?
heart block
What is adenosine used for?
terminate paroxysmal supraventricular tachycardia, acute atrial fibrillation and atrial flutter
What is verapamil used for?
prophylaxis of atrial flutter and atrial fibrillation
How is lignocaine administered?
IV
What is the mechanism of action of class IV drugs?
target calcium channels - slow conduction in SA and AV nodes - decreased force of cardiac contraction
What is digoxin used for?
atrial fibrillation
What is lignocaine used for?
ventricular arrhythmias following MI
What is the mechanism of action of amiodarone?
supresses re-entry
What is procainamide used for?
ventricular arrhythmias post MI
What is the mechanism of action of class I drugs?
block open and inactivated sodium channels - dissociate in diastole
What are the side effects of long term use of amiodarone?
pulmonary fibrosis, thyroid disorders, photosensitivity reactions, peripheral neuropathy
What class IB drug only blocks inactivated sodium channels?
lignocaine
What are propranolol and atenolol used for?
control supraventricular tachycardia
What is the mechanism of action of class IA drugs?
moderate association and dissociation rate - slow rise of AP - prolong refractory period
How is digoxin administered?
IV infusion or oral
What class is lignocaine?
IB
What is the mechanism of action of propranolol and atenolol?
supress excess sympathetic drive that may trigger ventricular tachycardia
Why do class I drugs have a greater effect in tachycardia?
more time in open and inactivated state
What is the mechanism of action of digoxin?
stimulates vagal activity - slows conduction and prolongs refractory period in AV node and bundle of His
What class is amiodarone?
class III, has class IA, II and IV actions
What is amiodarone used for?
supraventricular and ventricular tachycardia, congestive heart failure, reduces mortality post MI
What is flecainide used for?
prophylaxis of paroxysmal atrial fibrillation
What is the mechanism of action of class II drugs?
decrease rate of depolarisation in SA and AV nodes
What class is dispoyramide?
IA
What class of drugs are beta blockers?
class II
Why do class I drugs act preferentially on ischaemic tissues?
longer AP duration - more time in inactivate state
What class id procainamide?
class IA
How is verapamil administered?
oral
What class is flecainide?
class IC
Why is amiodarone pro arrhythmic?
Lengthens QT interval
