Prior to administration of the first dose, the corrected QT (QTc) must be determined. If the QTc is greater than 440 msec (or 500 msec in patients with ventricular conduction abnormalities),<unk>  is contraindicated. If heart rate is less than 60 bpm, the uncorrected QT interval should be used. After each subsequent dose of<unk> , QTc should be determined and dosing should be adjusted. If at any time after the second dose of<unk>  the QTc is greater than 500 msec (550 msec in patients with ventricular conduction abnormalities),<unk>  should be discontinued.
Dofetilide
Ibutilide
Sotalol
Flecainide
Verapamil
Amiodarone
Nortilidine
Procainamide