Simultaneous quantification of 6,7-di-hydroxyligustilide and gastrodin in rat plasma by LC-MS: Application to pharmacokinetic study of Tianshu capsule

A LC-MS method was developed and validated for simultaneous determination of 6, 7-di-hydroxyligustilide and gastrodin in rat plasma, and which was subsequently applied in the pharmacokinetic analysis of an administration of a Chinese herbal extract containing Chuanxiong Rhizoma and Gastrodia Elata Rhizome, i.e. TianShu capsule against migraine. The analytes were separated on a Kromasil C-18 column with a gradient elution program and detected without interference in the selected ion monitoring mode with positive electrospray ionization. The linear range was 0.010-10.0 mu g/mL for 6,7-di-hydroxyligustilide and 0.025-25.0 mu g/mL for gastrodin with the limit of quantitation of 0.01 and 0.025 mu g/mL, respectively. The intra-day and inter-day precisions for the entire validation were less than 14.7% of RSD. The pharmacokinetic parameters indicated that 6, 7-di-hydroxyligustilide and gastrodin are absorbed rapidly and reached a maximum concentration within one hour, which was consistent with the clinical requirements for the rapid relieving the symptoms of migraine.