9% had QTc interval >450 msec. The authors found a positive
dose-dependent relationship between methadone dose and QTc interval lengthening (Pearson r=0.37, p<0.01; multiple regression analysis B=0.37, p<0.01). A case control study was not performed. During the first month of methadone maintenance treatment, two deaths occurred among 3850 initiations of methadone maintenance. One patient died from intracranial bleeding and one cause of death was unknown. Anchersen et al.  concluded that death due to methadone during the first month of treatment was low and did not exceed 0.06 per 100 patient-years. The authors did not report the presence or absence of risk factors associated Inhibitors,research,lifescience,medical with TdP and attendant QTc interval prolongation in this paper but did look at their patients with QTc interval >500 msec in a second paper [Anchersen et al. 2010]. Anchersen et al.  provided a detailed review of their earlier subjects with QTc interval >500 msec with a particular focus on risk factors. Assessment included a detailed medical Inhibitors,research,lifescience,medical and cardiac history, genetic testing for the five most common long QT syndrome mutations, cardiac exercise testing and 24-hour Holter selleck monitor records. The authors assessed seven subjects and found that two were heterozygous long QT syndrome mutation
Inhibitors,research,lifescience,medical carriers who had both experienced cardiac complaints before and during opioid maintenance treatment. The authors detected no additional risk factor among these seven patients. In six subjects, QTc intervals fluctuated widely during 24-hour Holter monitor recording and exercise testing [Anchersen et
Inhibitors,research,lifescience,medical al. 2010]. Methadone-associated QTc interval prolongation More than 80% of patients receiving long-term methadone maintenance therapy may have QTc interval Inhibitors,research,lifescience,medical prolongation compared with reference values for patients of the same age and sex and there may be no correlation between QTc interval measurement and methadone dose [Maremmani et al. 2005]. However, others have reported a positive relationship between methadone dose and QTc interval duration [Kornick et al. 2003; Krantz et al. 2003]. Among our 21 cases of methadone-associated TdP, we failed to identify any relationship between QTc interval prolongation and methadone dose. Perhaps, multiple risk factors present may explain this finding. A paper recently published by Roy et al.  studied 180 subjects (69.1% men) in a methadone maintenance therapy program. Mean see more QTc interval was 420.9 ± 21.1 msec and the mean daily methadone dose was 80.4 ± 27.7 mg. There was no significant correlation between these two measurements (p = 0.33) with 8.8% of patients demonstrating QTc interval prolongation (8.3% men and 0.5% women). In contrast to the uneven findings of the relationship between QTc interval prolongation among TdP patients and methadone dose in our and other studies, Miceli et al.