Development and validation of an LC-MS/MS method for the determination of bullatine A in rat plasma: application to a pharmacokinetic study.

Bullatine A is a diterpenoid alkaloid of Xue-Shang-Yi-Zhi-Hao (Aconitum brachypodum), which is widely used in traditional Chinese medicine for the treatment of rheumatism and pain. The plasma levels of bullatine A were measured by a rapid and sensitive LC-MS/MS method. Samples were prepared using acetonitrile precipitation and the separation of bullatine A was achieved on a Capcell Pak MG-C18 column by isocratic elution using acetonitrile (phase A) and 0.1% formic acid (phase B, pH 4.0; A:B, 30:70, v/v) as the mobile phase at a flow rate of 0.5 mL/min. Detection was performed on a triple-quadrupole tandem mass spectrometer by multiple-reaction monitoring of the transitions at m/z 344.2 → 105.2 for bullatine A and m/z 256.2 → 167.1 for the internal standard. The linearity was found to be within the concentration range of 1.32-440 ng/mL with a lower limit of quantification of 1.32 ng/mL. Only 1.3 min was needed for an each analytical run. This method was successfully applied in the determination of the active component bullatine A in rat plasma after intramuscular administration of A. brachypodum injection.