Torsade de pointes associated with very-high-dose methadone

Area of Science:

• Cardiology
• Pharmacology
• Clinical Medicine

Background:

• Methadone is a key treatment for opioid dependence and pain.
• A related drug, levacetylmethadol, was withdrawn due to torsade de pointes risk.
• No prior link between methadone and this arrhythmia was established.

Purpose of the Study:

• To investigate methadone-associated torsade de pointes in a patient cohort.
• To identify risk factors and clinical characteristics of this adverse event.

Main Methods:

• Retrospective case series design.
• Data collected from methadone maintenance programs and a pain center.
• Included 17 patients with methadone use and torsade de pointes.
• Assessed QTc interval and co-existing arrhythmia risk factors.

Main Results:

• Mean daily methadone dose was high (397 mg).
• Mean QTc interval was significantly prolonged (615 msec).
• Most patients (14/17) had predisposing risk factors.
• 14 patients received pacemakers or defibrillators; all survived.

Conclusions:

• Very-high-dose methadone may be associated with torsade de pointes.
• Further research is crucial, especially with methadone's expanding use in primary care.