A novel mixed micelle gel with thermo-sensitive property for the local delivery of docetaxel.

In the present study, we incorporated docetaxel (DTX) into an injectable thermo-sensitive mixed micelle gel (MMG). It was found that the mixed micelle composed of Pluronic F127 (PF127) and Tween 80 overcame the problem of PF127 micelle on physical stability and drug release due to the low solubilization capacity of PF127 for the high lipophility of DTX molecules. Then, DTX MMG was characterized in vitro and in vivo, compared with DTX PF127 gel and free DTX. The sulforhodamine B (SRB) staining assay in both human breast cancer MCF-7 and ovarian cancer SKOV-3 cell lines revealed that DTX loaded mixed micelles generated the highest cytotoxicity. Different local administrations, including intratumoral (i.t.), peritumoral (p.t.) and subcutaneous (s.c.) injections were compared and optimized in SKOV-3 ovarian tumor-xenograft bearing mice. Among these, the i.t. delivery of DTX MMG proved to be most effective. Moreover, it was demonstrated in the pharmacokinetic evaluation of DTX MMG that DTX remained in the tumor mass for more than six days post i.t. injection; likewise, we found that it correlated well with the in vitro release. During the observation period, there were no deaths, visible toxicity, nor obvious necrosis at the injection sites observed in all the animals tested. These results suggested that this injectable MMG system, provided a promising locally delivered vehicle for hydrophobic anti-tumor agents to increase their efficacy and thereby improved their therapeutic effect for clinical treatment.