Abstract: A simple,rapid,sensitive and reliable ultra-fast liquid chromatography-electrospray ionization-tandem mass spectrometry(UFLC-ESI-MS/MS)method was developed for quantifying helicid in rat plasma.The lower limit of quantitation(LLOQ)was 0.1 ng/mL and total run time was within 2 min.The method was validated in terms of selectivity,linearity,accuracy and precision,extraction recoveries,matrix effects,carry-over,cross talk,dilution integrity,stability and incurred sample reanalysis(ISR).Using this validated method,bioavailability,influence of different dosage levels and multiple-doses on pharmacokinetic behaviors of helicid were investigated for the first time.Results showed that after intragastric(i.g.)administration at three dose levels(25,50,100 mg/kg),helicid exhibited a linear pharmacokinetic behavior.Bioavailability at three dose levels was 48.34%,48.17% and 60.34%,respectively.Meanwhile,besides T_max,multiple-dosing of helicid(50 mg/kg,tid)for 6 days seemed not significantly affect the PK profiles and accumulation didn’t occur.

Key words: helicid, UFLC-ESI-MS/MS, bioavailability, Pharmacokinetics