Antiarrhythmics

Lidocaine

Adult Dosing

• Loading dose = 1-1.5 mg/kg
  • Additional boluses of 0.5-0.75 mg/kg q5-10min up to max of 3mg/kg
  • If effective start infusion of 2mg/min

Contraindications

• High SA or AV block

Indications

• Treatment of ventricular arrhythmias and ectopy
  • Considered 2nd-line to amiodarone for tx of V-fib and pulseless v-tach

Mechanism of Action

• Class Ib
  • Binds to fast Na channels in inactive state thereby inhibiting recovery after repolarization
  • Acts preferentially on ischemic tissue
    • Elevates V-fib threshold
    • Suppresses ventricular ectopy
• Little effect on vascular tone, contractility or cardiac output

Adverse Drug Rxns

• CNS
  • Abrupt change in MS, drowsiness, confusion, sz

Kinetics

• Onset of action = 45-90s
• Duration of action = 10-20min

Procainamide

Adult Dosing

• Continuous infusion rate has fewer adverse effects
  • 20mg/min for 25-30min
    • If effective start cont infusion of 1-4mg/min

Contraindications

• Not recommended for V-fib or pulseless V-tach (too long to dose)
• 2nd or 3rd AV block
• Severe glycoside intoxication
• Prolonged QT
• Myasthenia gravis

Indications

• Wide-complex tachycardia of unknown type (in pts w/ preserved LV function)
• Stable V-tach

Mechanism of Action

• Class Ia
  • Binds to fast Na channels in inactive state thereby inhibiting recovery after repolarization
  • Prolongs action potential and reduces speed of impulse conduction
    • Depresses myocardial conduction
  • May act as negative inotrope, cause hypotension (peripheral vasodilation)

Adverse Drug Rxns

• Myocardial depression
• Watch for QRS/QT prolongation, V-tach, Vfib, complete AV block, torsades

Kinetics

• Onset of action = 5-10min

Source

Tintinalli