A METHOD FOR RAPID-DETERMINATION OF ZOTEPINE BY GAS-CHROMATOGRAPHY MASS-SPECTROMETRY

A rapid and sensitive method using solid-phase extraction and gas chro matography-mass spectrometry (GC-MS) has been developed for the determ ination of zotepine (ZTP). an atypical neuroleptic, in human plasma. T he detection limit of ZTP was 1 mu g/L. Standard curves over the conce ntration range from 2.5 to 100 mu g/L had a good linearity. Intraassay variability ranged from 2.2 to 3.3% and interassay variability from 3 .5 to 6.6% at the concentration range of 5-75 mu g/L. Our preliminary data of single-dose kinetics of ZTP by using this method suggested tha t the peak time and elimination half-life was much longer than previou sly reported, and that there appeared to be a second peak after 10-12 h of ZTP administration, indicating the possibility of the presence of enterohepatic recirculation.