Amiodarone has brought a major change in the medical management of ventricular arrhythmias over the last few decades. It is a powerful antiarrhytmic drug , with all class 1 -4 action (of vaugan williams classification.) It has sodium , pottasium, calcium and beta blocking properties. Hence there is no surprise, amiodarone is aptly called a broadspectrum anti arrhythmic as it acts on many of the cardiac receptors .
Of course , the major action is thought to be pottasium channel blocking effect(Class 3) that prolongs the action potential duration and refractory period resulting in termination of many re entrant arrhythmias. While , amiodarone by structure resembles thyroid hormone, takes a long time to reach the steady state plasma levels .Oral amiodarone takes up to a week time to exert it’s action.
If amiodarone is a slow acting drug , is it not surprising , Why IV amiodarone is given in the emergency managment of VT ?
Typically , there is difference between the mechanism of action between oral and IV amiodarone
The class 3 property of amiodarone , is a late observation following oral adminstration. QT prolongation rarely occurs following bolus iv amiodarone. So , VT terminating effect is thought to be some thing , other than class 3 action. Many believe the combined beta and calcium channel blocking effect could be responsible for rapid reversion of ventricular arrhythmias. The sodium channel blocking action with fast kineticks may also contribute.
Final message.
While amiodarone is a prototype class 3 anti arrhythmic drug, it’s VT terminating property may be , attibutible to other class action. mean while , the Class 3 action is responsible for long term prevention of VT/VF .
Amiodarone has brought a major change in the medical management of ventricular arrhythmias over the last few decades. It is a powerful antiarrhytmic drug , with all class 1 -4 action (of vaugan williams classification.) It has sodium , pottasium, calcium and beta blocking properties. Hence there is no surprise, amiodarone is aptly called a broadspectrum anti arrhythmic as it acts on many of the cardiac receptors .
Of course , the major action is thought to be pottasium channel blocking effect(Class 3) that prolongs the action potential duration and refractory period resulting in termination of many re entrant arrhythmias. While , amiodarone by structure resembles thyroid hormone, takes a long time to reach the steady state plasma levels .Oral amiodarone takes up to a week time to exert it’s action.
If amiodarone is a slow acting drug , is it not surprising , Why IV amiodarone is given in the emergency managment of VT ?
Typically , there is difference between the mechanism of action between oral and IV amiodarone
The class 3 property of amiodarone , is a late observation following oral adminstration. QT prolongation rarely occurs following bolus iv amiodarone. So , VT terminating effect is thought to be some thing , other than class 3 action. Many believe the combined beta and calcium channel blocking effect could be responsible for rapid reversion of ventricular arrhythmias. The sodium channel blocking action with fast kineticks may also contribute.
Final message.
While amiodarone is a prototype class 3 anti arrhythmic drug, it’s VT terminating property may be , attibutible to other class action. mean while , the Class 3 action is responsible for long term prevention of VT/VF .