Drug release mechanism of paclitaxel from a chitosan–lipid implant system: Effect of swelling, degradation and morphology

Localized and sustained delivery of anti-cancer agents to the tumor site has great potential for the treatment of solid tumors. A chitosan–egg phosphatidylcholine (chitosan–ePC) implant system containing PLA-b-PEG/PLA nanoparticles has been developed for the delivery of paclitaxel to treat ovarian cancer. Production of volumes of ascites fluid in the peritoneal cavity is a physical manifestation of ovarian cancer. In vitro release studies of paclitaxel from the implant were conducted in various fluids including human ascites fluid. A strong correlation (r2 = 0.977) was found between the release of paclitaxel in ascites fluid and PBS containing lysozyme (pH 7.4) at 37 °C. The drug release mechanism for this system was proposed based on swelling, degradation and morphology data. In addition, in vitro release of paclitaxel was found to be a good indicator of the in vivo release profile (correlation between release rates: r2 = 0.965). Release of paclitaxel was found to be sustained over a four-week period following implantation of the chitosan–ePC system into the peritoneal cavity of healthy Balb/C mice. Also, the concentrations of paclitaxel in both plasma and tissues (e.g. liver, kidney and small intestine) were found to be relatively constant.