Pharmacokinetics and biodistribution of paclitaxel-loaded pluronic P105/L101 mixed polymeric micelles.

A mixed polymeric micelle formulation of paclitaxel (PTX) has been developed with the purpose of improving the solubility and prolonging the time of blood circulation of PTX in comparison to current Taxol injection. The mixed micelles were prepared by thin-film method using a nonionic surfactant Pluronic P105, L101 and PTX. The mean size of PTX-loaded mixed micelles was 185 nm with narrow size distribution shown by a dynamic light scattering sizer and a transmission electron microscopy. The in vitro release profiles indicated that PTX release from the mixed micelles exhibited a sustained release behavior. A similar phenomenon was also observed in a pharmacokinetic assessment in rats, in which t(1/2beta) and AUC of the mixed micelle formulation were 5.5 and 4.9-fold higher than that of Taxol injection. The biodistribution study in mice showed that the PTX-loaded mixed micelles not only decreased drug uptake by liver, but also prolonged drug retention in blood, and increased distribution of the drug in lung, spleen and kidney. These results suggested that the mixed polymeric micelles may efficiently load, protect and retain PTX in both in vitro and in vivo environments, and could be a useful drug carrier for intravenous administration of PTX.