Pharmacokinetic analysis of levo-tetrahydropalmatine in rabbit plasma by rapid sample preparation and liquid chromatography–tandem mass spectrometry.

A rapid extraction method was developed and validated for levo-tetrahydropalmatine ( l -THP) determination in rabbit plasma by liquid chromatography tandem–mass spectrometry (LC–MS/MS). The sample preparation included a single-step acetonitrile extraction and salting out liquid–liquid partitioning from the water in plasma with MgSO 4 . Berberine was used as internal standard. The mass spectrometry source was negative electrospray ionization. The method showed good performance in the concentration range from 5 to 200 ng mL −1 . The limit of quantification (LOQ) was 1 ng mL −1 . The method was successfully applied to a pharmacokinetic study in rabbit comparing the two drug formulation of l -THP including the raw material and the self-microemulsifying drug delivery system pellet. [ABSTRACT FROM AUTHOR]