[sixty one] Like quite a few other cardiotoxic drugs, methadone blocks the hERG K+ channel. The 2 enantiomers of methadone inhibit hERG channels with different potency. Dextromethadone, which is less strong being an opioid, is much more strong at blocking the hERG channel with an IC50 of ~12 ?M. Levomethadone incorporates a lower affinity, with an