Gender‐Specific Differences in Susceptibility to Low‐Dose Methadone‐Associated QTc Prolongation in Patients with Heroin Dependence

Abstract

Methadone is associated with QTc prolongation and sudden death in susceptible patients. We sought to investigate whether there is a gender-based difference in susceptibility to methadone-associated QTc prolongation in heroin-dependent patients receiving a low-dose treatment regimen. A cross-sectional assessment of dose and gender effects was performed in 283 patients (229 males, 54 females) who received a 12-lead ECG for QTc measurement 59 days (interquartile range: 36-288 days) after methadone treatment. To determine the effects of methadone over time, a subset of 150 participants (126 men, 24 women) who underwent a 12-lead ECG before and 37 days (interquartile range: 32-44 days) after methadone treatment were selected. In the cross-sectional study, a significant dose-dependent interaction between methadone and QTc (r = 0.201, P = 0.0007) was observed in individuals receiving a median methadone dose of 40 mg/day (interquartile range: 30-60 mg/day). The methadone-QTc correlation was significant in males (r = 0.210, P = 0.0014) but not in females (r = 0.164, P = 0.2363). The longitudinal assessment of methadone's effects over a 6-month period showed that 60.7% of individuals experienced an increase in QTc compared to baseline data. The adjusted QTc significantly increased from 418.5 to 426.9 milliseconds in males (P < 0.0001), compared to an insignificant change in females (437.7 milliseconds vs 441.1 milliseconds, P = 0.468). Low-dose methadone therapy shows dose-dependent QTc prolongation and is associated with significant QTc lengthening within 6 months of treatment initiation. Men are more susceptible than women to low-dose methadone-associated QTc prolongation.