S-Methadone
dextromethadone
What it isThe S-enantiomer of methadone, with weak NMDA antagonism but little mu activity.
Why this oneIt carries most of methadone’s hERG blockade, so it explains the QT risk without contributing analgesia.
What limits itThis asymmetry is the argument for using the R-enantiomer alone, as some European countries do.
FDA-approved for
- inactive enantiomer of methadone
NO BOXED WARNINGS
Principal riskMost of racemic methadone’s hERG/QT liability
Classes and tags
Clinical profile
Defining liabilityInvestigational safety, QT signal and CYP2D6 interactions