Dofetilide in Overdose: A Case Series from Poison Center Data

Dofetilide is a class III antiarrhythmic used for treating atrial dysrhythmias. Though its adverse effects are well described in routine use, very little is known about dofetilide toxicity in overdose. This is a retrospective case series of consecutive patients reported to our poison center after dofetilide overdose. Twenty-seven cases were included. Seventeen patients were treated at a healthcare facility, and of these, eight were admitted. Twenty-one patients took one extra capsule, four took someone else's medication, one took three extra capsules, and one had a large intentional overdose. Ten patients had co-ingestants reported, including three QT-prolonging agents. No one required cardioversion, defibrillation, CPR, or overdrive pacing. The patient who reported taking 90 times his usual dose in suicide attempt was the only patient to have significant clinical effects. He experienced an 8-beat run of non-sustained ventricular tachycardia, frequent multifocal PVCs, and ventricular bigeminy. He received magnesium sulfate and potassium chloride supplementation. In this series, unintentional small overdoses did not result in significant clinical effects and were often managed successfully at home, despite the fact that information showing a single capsule can cause torsades. This study is limited by its small sample size, retrospective design, and reliance on incomplete information.