Effects of Switching From Racemic Methadone to R-methadone on QTc Intervals

The Study of Potential Normalization of Cardiac Rhythm Following Drug Exchange From Chimeric Methadone to Active Methadone

Effects of switching from racemic methadone to R-methadone on serum methadone concentrations and QTc intervals

Racemic methadone may prolong the QTc interval, which is associated with fatal arrhythmias. In vitro studies have shown that R-methadone has less inhibitory effect than S-methadone on the voltage-gated potassium channel current, and is thus thought to have less effect on the QTc interval.

The investigators hypothesized that switching from racemic to R-methadone would reduce the methadone serum concentration and also its effect on the QTc interval.

Inclusion Criteria:

• Stabilized on daily methadone dose
• Not using other drugs of abuse
• QTc-time recorded automatically, patient inclusion if QTc interval was greater or equal to 450 ms
• Older than 18 years
• Can sign and understand a written Consent

Exclusion Criteria:

• Can not cooperate regarding observed daily drug intake
• Serious psychiatric disease
• Untreated serious somatic disease
• Pregnancy