Critical
Amiodarone × Methadone
Class III antiarrhythmics (Vaughan Williams)×Synthetic opioid, full mu-receptor agonist
Mechanism
Additive QT prolongation from two strong QT prolongers + amiodarone inhibits CYP3A4 (methadone rises).
Symptoms
QTc above 500 ms, syncope, torsades de pointes risk.
Management
Combination contraindicated.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Sources
- FDA: Cordarone (amiodarone) prescribing information (2018)
- FDA: Dolophine (methadone) prescribing information – QT prolongation and CYP interactions (2014)– FDA Dolophine label, Boxed Warning – QT prolongation, serious cardiac arrhythmias
- FDA: Dolophine (methadone) prescribing information (2014)