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Clinical pharmacy 2024/2025 Level 3 Pharm D Pharmacology 1 (PO 502)

Lidocaine

 Local anesthetic & antiarrhythmic.

 Antiarrhythmic action:

➢ Na+ channel blockade
Effective in ventricular arrhythmias only why?

➢ Does not affect atrial electrophysiology.
➢ More effective against arrhythmias associated with ischemia as ventricular arrhythmias.
➢ N.B. Class IB is more effective in VT because of use dependence in which inactivated
Na channels are available more than in normal sinus rhythm.

 Pharmacokinetics of lidocaine
:
 It should be used by intravenous route because of its extensive first-pass metabolism

(F= 30 %)
 Pass BBB producing central effects .

 Uses :
A. Lidocaine is the drug of choice in emergency treatment of ventricular arrhythmias

(I.V.) in cardiac surgery, cardiac ischemia or MI, digitalis toxicity.
B. Local anesthetic (used locally)

:
 ADRs
➢ CNS stimulation: disorientation, convulsion & post-ictal depression .

 Advantages :

➢ The least cardiotoxic & least hypotensive antiarrhythmic drug.

Flecainide, Propafenone

 Mechanism of action :

+
➢ Class IC, blocking Na channels

 USES:

➢ Only approved for refractory ventricular arrhythmias as Premature
ventricular contractions & WPW syndrome

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