Antidysrhythmics William Eggleston, PharmD Fellow in Clinical Toxicology Upstate NY Poison Center

Objectives Discuss the differing mechanisms of class I and class III antidysrhythmics Compare clinical manifestations of antidysrhythmic toxicity Formulate a treatment strategy for the management of antidysrhythmic toxicity

Sudden Cardiac Death Huikuri HV et al. N Engl J Med. 2001; 345(20):1473-82

K+ Ca2+ L-type Ito K+ IKr Na+

Class I Antidysrhythmics Na+

Class I Antidysrhythmics Recovery QRS Inotropy

Class Ia Na+ QRS/QTc

Holford NH et al. Br J Clin Pharmacol. 1981; 11(2):187-95

Class Ia IKR Procainamide Quinine/Quinidine Disopyramide Included in ACLS NAPA Quinine/Quinidine Disopyramide K+ K+ IKR

Class Ib Na+ QTc

Rosen MR et al. Am Heart J. 1976; 91(2):191-202

Class Ib Lidocaine Phenytoin Refractory wide QRS Seizures CV toxicity = propylene glycol

Class Ic Na+ QRS

Fonck K et al. J Toxicol Clin Toxicol. 1998; 36(3):247-51

Class Ic Propafenone Flecainide Β-adrenergic antagonist CAST Initiated inpatient

ECG Findings RBBB

ECG Assessment QRS >100 ms QRS >160 ms Boehnert MT et al. N Engl J Med. 1985; 313(8):474-9

Managment

SV Preload

Class III Antidysrhythmics K+ Ca2+ L-type Ito K+ IKr Na+

Class III Antidysrhythmics K+ IKr

Class III Antidysrhythmics Amiodarone 40% mw = iodine Vfib/Vtach Block L-type Ca2+ channels Dofetilide Ibutilide