Paclitaxel carried by long circulating microemulsions used for metronomic chemotherapy of cancer

Long circulating paclitaxel microemulsions (TXL-M) were prepared and its anticancer effect was evaluated in metronomic chemotherapy of cancer using animal tumor models.  In TXL-M, paclitaxel was   dissolved in vitamin E and polylene glycol derivative of distearoylphosphatidyl ethanolamine (PEG-DSPE) was used as surfactant.  The shape and particle size distribution of TXL-M were evaluated using an electronic    microscope and a laser size scanner.  The toxicity comparisons of TXL-M and paclitaxel were conducted using mice.  Its anticancer effect and long circulation were evaluated using animal tumor model in C57BL/6 mice.  The average diameter of TXL-M was (98.6 ± 11.2) nm and its zeta potential was (−32.4 ± 6.8) mV.  Compared with paclitaxel, TXL-M showed lower toxicity.  When used in metronomic chemotherapy of cancer, TXL-M showed longer circulation time in the blood and greater anticancer effect than paclitaxel.  Thus, TXL-M is a better candidate for metronomic chemotherapy of cancer than paclitaxel injection.