Investigation of the neuroleptic drug haloperidol and its metabolites using tandem mass spectrometry

Abstract The in vitro metabolism of haloperidol, a clinically utilized neuroleptic drug, was investigated using guinea pig derived hepatic microsomal incubates. By employing a combination of reversed phase HPLC and tandem mass spectrometry, it was revealed that haloperidol was metabolized to at least eight different compounds, including the proposed dopaminergic toxin 4-(4-chlorophenyl)-1-[4-(4-fluorophenyl)-4- oxobutyl]-pyridinium species and an intermediate metabolite 4-(4-chlorophenyl)-1-[4-(4-fluorophenyl)-4- oxobutyl]- 1,2,3,6-tetrahydropyridine.