Determination of bulleyaconitine A in plasma by a sensitive LC–MS/MS method and its application to an oral pharmacokinetic study in rats

A sensitive liquid chromatography–tandem mass spectrometry (LC–MS/MS) method was developed and validated for the quantification of bulleyaconitine A (BLA) concentration in rat plasma. An aliquot of 100 μL plasma sample was prepared by liquid–liquid extraction with diethyl ether. Chromatographic separation was accomplished on a Phenomenex Luna C18 column (50 mm × 2.00 mm, 5 μm) utilizing a isocratic mobile phase consisting of (A) 0.1% formic acid in methanol and (B) formic acid in water. Detection was performed by multiple reaction monitoring (MRM) mode using electrospray ionization in the positive ion mode. The optimized fragmentation transitions for MRM were m/z 644.4 → m/z 584.3 for BLA and m/z 632.4 → m/z 572.3 for mesaconitine (IS). The method was linear over the concentration range of 0.02–20.0 ng/mL. The intra and inter-day variance are less than 6.1% and accuracy is within ±9.0%. The validated method was successfully applied to pharmacokinetic study in rat after single oral administration of 40 μg/kg of BLA and the oral pharmacokinetic data of BLA have been demonstrated for the first time.