Comparative Evaluation of Different Methadone Dosages on Qt Interval

Objective: Methadone is used for the treatment of opioid dependency. Methadone causes QTc prolongation and occasionally torsade de pointes. Because of the wide availability of methadone in methadone maintenance treatment (MMT) centers, dose-related effects of methadone on QT interval were evaluated. Methods: The study was a clinical trial. Ninety patients who were under methadone maintenance treatment in the MMT center of Noor hospital and Ghaedi Clinic were evaluated. According to methadone doses the patients were divided into three groups (0-59 mg, 60-109 mg, 110-150 mg). Twelve-lead electrocardiograms (ECOs) were performed in patients at both baseline and after the maximum daily doses of methadone therapy. The ECGs were manually interpreted. The QTc intervals were calculated for each patient. In different groups, comparison of mean differences of QTc interval between baseline and follow up were analyzed by ANOVA. Results: There were significant differences between means of QTC interval before and after treatment with methadone in all groups. Methadone modestly increased QTc interval. Conclusion: Although QTc interval prolongation may occur after methadone treatment, the risk for torsade de pointes arrhythmia is low.