Major
Amiodarone × Ondansetron
Class III antiarrhythmics (Vaughan Williams)×5-HT3 serotonin receptor antagonist
Mechanism
Ondansetron prolongs QT 10-15 ms, amiodarone 30-50 ms. Additive torsades risk.
Symptoms
QTc above 500 ms, syncope, torsades de pointes risk.
Management
Alternative – metoclopramide. If ondansetron needed – single IV dose no higher than 8 mg.
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.