We thank Drs Krantz and Mehler for their comments and for highlighting this important problem. Indeed, we are aware of the arrhythmogenic effects of opioid antagonists, and might also highlight that although the authors' own article1 showing that "very high-dose" methadone can cause torsade de points ventricular tachycardia, the actual dosages reported actually range from 65 to 1000 mg/d. Thus, clinicians should be aware that a range of doses of potentially proarrhythmic drugs may be dangerous in patients predisposed to this complication.
Goldschlager N, Epstein AE. Synthetic Opioids and QT Prolongation—Reply. Arch Intern Med. 2003;163(13):1615. doi:10.1001/archinte.163.13.1615-a