Effects of norquetiapine, the active metabolite of quetiapine, on cloned hERG potassium channels.

•Quetiapine is widely used for the treatment of schizophrenia.•Norquetiapine is a major active metabolite of quetiapine in humans.•Norquetiapine inhibited hERG in a concentration-dependent manner.•Norquetiapine inhibited hERG currents at supratherapeutic concentrations.•Norquetiapine preferentially interacted with the activated states of hERG channels.