Determination of in vitro CYP450 activity with nifedipine as a probe drug by HPLC-MS

OBJECTIVE To establish a HPLC/MS method to determine microsomes activity in vitro using nifedipine as a probe drug. METHODS Nifedipine was incubated with rat or Beagle dog liver microsomes in vitro, oxidized nifedipine were determined by HPLC-MS. A SHIMADZU-ODS ( 2.0 mm* 150 mm) column as chromatographic column. The mobile phase consisted of methanol-water (55 '• 45) at a flow rate of 0.2 mL/min"1. MS detector was set as positive selective ion scan mode at m/z 345. RESULTS The retention time of oxidized nifedipine was 7.15 min. The detection limit in rat or Beagle dog liver microsomes was 3 ug'L"1 for oxidized nifedipine (S/N=3), and the linear range was over the range of 0.01-10 mg'L-1. The recovery and accuracy satisfied the requirement of detection for oxidized nifedipine in rat and Beagle dog liver microsomes. CONCLUSION Oxidized nifedipine can be detected accurately and precisely by using the HPLC/MS method.