Pharmacokinetic comparative study of tetramethylpyrazine and ferulic acid and their compatibility with different concentration of gastrodin and gastrodigenin on blood-stasis migraine model by blood-brain microdialysis method.

Tianma pills, a traditional formula made from Ligusticum chuanxiong and Gastrodia elata, are efficacious for the treatment of primary headache. Tetramethylpyrazine (TMP) and Ferulic acid (FA) are the bioactive ingredients of Ligusticum chuanxiong, while Gastrodin and Gastrodigenin are the bioactive ingredients of Gastrodia elata. Pharmacokinetic assessment of TMP, FA, gastrodin or gastrodigenin in blood or brain interstitial fluid (BIF) has been reported in healthy animals. However, the pharmacokinetic properties of TMP and FA have not been studied when they are co-administered in a blood-stasis migraine model. The present research investigated the pharmacokinetic behavior of TMP and FA after oral administration in the presence of different concentrations of gastrodin and gastrodigenin in a blood-stasis migraine model. Pharmacokinetic parameters were determined using blood-brain microdialysis in combination with the UHPLC-MS method. Compared to the control group, in which TMP and FA were administrated without gastrodin or gastrodigenin, the T_1/2, MRT, C_max and AUC_0-∞ of TMP and FA were increased. These results indicate that varying concentrations of gastrodin and gastrodigenin play an important role in affecting the pharmacokinetics of TMP and FA. Low concentrations of gastrodin and gastrodigenin (similar to those found in Tianma pills) were more efficacious, validating the utility of the ancient formulation.