Abstract: Objective To evaluate the effect of Radix euphorbiae pekinensis extract on the permeability and bioavailability of
paclitaxel co-administered orally. Methods Based on Ussing Chamber and in vivo experiment, the permeability and
bioavailability of paclitaxel were evaluated after oral co-administration with radix euphorbiae pekinensis in rats. The contents
of paclitaxel in the permeates and the blood samples were determined using HPLC and LC-MS/MS method, respectively.
Results In Radix euphorbiae pekinensis co-administration group, the Papp of the mucosal-to-serosal (M-S) transport or
serosal-to-mucosal transport (S-M) of paclitaxel in the jejunum or ileum segment differed significantly from those in verapamil
co-administration group and blank control group (P<0.05), but the Papp of S-M transport in the colon showed no significant
difference from that in the blank control group. In the blank group, the average absolute bioavailability (AB% ) of orally
administered paclitaxel was only 2.81%, compared to that of 7.63% in radix euphorbiae pekinensis group. The average AB% in
verapamil group was about 1.5 times that of the blank group. Conclusion Co-administration of Radix euphorbiae pekinensis
extract can increase the bioavailability of orally administered paclitaxel.