Pharmacokinetics and Oral Bioavailability of Paclitaxel Microemulsion in Rats

The objectives of this study were to formulate oral paclitaxel microemulsion and to compare the bioavailability of paclitaxel in the microemulsion formulation from the commercially available $Taxol^{(R)}$ formulation. Paclitaxel microemulsion was formulated with much less amount of Cremophor $EL^{TM}$ as compared with $Taxol^{(R)}$ to reduce severe adverse reactions produced by Cremophor $EL^{TM}$. The area under the plasma concentration-time curve from 0 hr to 24 hr ($AUC_{0-24}$), maximum plasma concentration ($C_{max}$), and relative bioavailability of palcitaxel microemulsion were increased as compared with $Taxol^{(R)}$ after oral administration. The time required to reach $C_{max}\;(T_{max})$ of palcitaxel microemulsion was significantly shorter than $Taxol^{(R)}$ following oral administration. These results suggest the faster intestinal absorption and the enhanced oral bioavailability of paclitaxel in the microemulsion formulation.