Answer
Methadone can prolong the QT interval and rarely cause a dangerous ventricular rhythm. ECG assessment is particularly relevant with cardiac disease, electrolyte disturbance or interacting medicines.
Sources for this answer
- Methadone Mixture 1mg/ml — Current selected SmPCemc · Summary of Product Characteristics
General medicine information. Follow the instructions for your own medicine and speak to a pharmacist or clinician about your individual circumstances.