Pharmacokinetics of baicalin-phospholipid complex in rat plasma and brain tissues after intranasal and intravenous administration

The aim of this study is to determine whether baicalin can be transferred along the olfactory pathway to the brain after nasal administration of baicalin phospholipid (BP) complex to rats, thereby circumventing the blood brain barrier. The concentration of baicalin in plasma and different brain tissues (olfactory bulb, cerebral cortex, striatum and cerebellum) were measured by high-performance liquid chromatography (HPLC). The ratios of the area under the concentration-time curve (AUC) values of intranasal to intravenous administrations were 54.21 %, 240.59 %, 374.71 %, and 114.54 % in plasma, cerebral cortex, striatum, and cerebellum, respectively. In the olfactory bulb, the AUC values of intranasal to intravenous administrations were 3355.4^± 378.8 g/g^˙ min versus 0 g/g^˙ min following intravenous administration. The ratios of AUC values of intranasal to intravenous administrations were72.75 %, 240.59 %, 374.71 %, 114.54 % in plasma, cortex, striatum, cerebellum respetively. The proportion of baicalin in the brain tissues from the olfactory transfer was also calculated, and the result shows that, following intranasal administration, approximately 52.36 %–100 % baicalin content at 8 h was transported to the brain via the olfactory pathway. In conclusion, the BP complex is transferred into the olfactory bulb via the olfactory pathway in rats, and the BP complex intranasal delivery is a promising approach to protect against cerebral ischemic injury.