Adverse effects of antiarrythymic drugs

ADVERSE EFFECTS OF ANTIARRYTHMICS DRUGS

  • One of the most common and serious adverse cardiac effects is proarrhythmia (arrhythmia ironically precipitated by antiarrhythmic therapy) which can occur in 5-20% of patients treated with Class I and Class III drugs.
  • Class I drugs (Sodium-channel blockers):
    • Proarrhythmic effect
    • Dose-dependent negative inotropic effect
  • Subclass IA (especially quinidine) – Torsades de pointes ("twisting of the points"):
    • Usually occurs within the first week of therapy
    • Pre-existing prolonged QT intervals may be indicator of susceptibility
    • Potentiated by bradycardia
    • Often associated with concurrent electrolyte disturbances (hypokalemia, hypomagnesemia)
  • Subclass IC - Ventricular tachycardia
  • Class II drugs (Beta-blockers):
    • Sinus bradycardia
    • Atrioventricular block
    • Depression of left ventricular function
  • Class III drugs (Potassium-channel blockers):
    • Sinus bradycardia
    • Torsades de pointes
  • Class IV drugs (Calcium-channel blockers):
    • Atrioventricular block
    • Negative inotropic action
Last modified: Wednesday, 25 April 2012, 11:34 AM