[sixty one] Like a lot of other cardiotoxic drugs, methadone blocks the hERG K+ channel. The two enantiomers of methadone inhibit hERG channels with distinctive potency. Dextromethadone, that is significantly less strong as an opioid, is more potent at blocking the hERG channel with an IC50 of ~12 ?M. Levomethadone incorporates a lower affinity, wi