N-Desmethylolanzapine -d8 hydrochloride (N-Demethylolanzapine-d8 hydrochloride) is the deuterium labeled N-Desmethylolanzapine. N-Desmethylolanzapine is an antipsychotic drug. The formation of N-Desmethylolanzapine correlates with the level and activity of human liver flavin-containing monooxygenase (FMO3). N-Desmethylolanzapine can be used in the study of antipsychotic drugs.