avoid methadone in long QT patients

One possible adverse effect of methadone is prolongation of the corrected QT (QTc) interval, which can predispose patients to life-threatening cardiac arrhythmias, such as torsades de pointes. To reduce this risk, the American Pain Society and the Heart Rhythm Society recommend the following approach.

An electrocardiogram (ECG) should be obtained before initiating methadone in any patient who has a risk factor for QTc prolongation, such as structural heart disease, genetic predisposition, or use of other medications with QTc-prolonging properties.

If any patient’s methadone dose is increased to exceed 30 to 40 mg daily, they should undergo ECG soon after the increase. If the dose is further increased to reach 100 mg daily, another ECG should be obtained.

Methadone should not be used in patients with a QTc interval >500 msec and should be used only cautiously in those with QTc intervals between 450 and 500 msec.1

Footnotes

  1. NEJM Pain Management and Opioids ↩