Drug-Induced Long QT Syndrome in Injection Drug Users Receiving Methadone

Abstract

Background: Drug-induced long QT syndrome is a se-rious adverse drug reaction. Methadone prolongs the QT interval in vitro in a dose-dependent manner. In the in-patient setting, the frequency of QT interval prolonga-tion with methadone treatment, its dose dependence, and the importance of cofactors such as drug-drug interac-tions remain unknown. Methods: We performed a systematic, retrospective study comparing active or former intravenous drug us-ers receiving methadone and those not receiving metha-done among all patients hospitalized over a 5-year pe-riod in a tertiary care hospital. A total of 167 patients receiving methadone fulfilled the inclusion criteria and were compared with a control group of 80 injection drug users not receiving methadone. In addition to methadone dose, 15 demographic, biological, and phar-macological variables were considered as potential risk factors for QT prolongation.