A simple and selective UHPLC-MS/MS method for quantification of plantagoguanidinic acid in rat plasma and its application to a pharmacokinetic study

A simple, sensitive and specific UHPLC-MS/MS method for quantification of plantagoguanidinic acid (PGA) in rat plasma was applied to investigate the pharmacokinetic behavior in vivo, using protopine as internal standard. The chromatography was separated on a Phenomenex (R) Luna-C-18 column (2.1x150mm, 3.0m) within 7.0min using a mobile phase consisting of acetonitrile-0.1% formic acid solution under gradient elution at a flow rate of 0.4mL/min. Prepared samples were monitored by multiple reaction monitoring mode, with the target fragmentions m/z 226.284.2 for PGA and m/z 354.2188.9 for IS in positive electrospray ionization. The calibration curve of PGA was linear throughout the range 1-1000ng/mL (r=0.9962). The lower limit of quantitation in plasma for PGA was 0.1ng/mL, and the recovery was >88.6%. Intra- and interday accuracy ranged from -8.6 to 4.9%. Furthermore, this validated method was successfully used for a pre-clinical pharmacokinetic study of PGA at a single dose of 20 and 5mg/kg in rats via oral and intravenous administration. The study showed that PGA was absorpted rapidly and eliminated gradually with a greater absolute oral bioavailability of 70.1% in rats.