Abstract: AimTo establish a LC-MSⁿ method for the identification of anisodamine and its metabolites in rat feces. MethodsFeces samples were collected after single administration of 25 mg·kg^-1 anisodamine to rats, and dipped in water for 1 h. Samples were then extracted by ethyl acetate. The pretreated samples were separated on a reversed-phase C18 column using a mobile phase of methanol / 0.01% triethylamine (adjusted to pH 3.5 with formic acid) (60∶40, v/v) and detected by LC-MSⁿ. Identification of the metabolites and elucidation of their structures were performed by comparing their changes in molecular masses (ΔM), retention-times and full scan MSⁿ spectra with those of the parent drug and blank feces. ResultsThe parent drug and its seven metabolites (6β-hydroxytropine, nor-6β-hydroxytropine, aponoranisodamine, apoanisodamine, noranisodamine and hydroxyanisodamine, tropic acid) were found in rat feces. ConclusionThis method is sensitive, rapid, simple, effective, and suitable for the rapid identification of drug and its metabolites in biologic samples.