In vitro and in vivo characterization of a novel biocompatible polymer-lipid implant system for the sustained delivery of paclitaxel.

Recently, a novel chitosan-based implantable formulation (chitosan-ePC) was developed to provide controlled, local release of paclitaxel (PTX) for the treatment of ovarian tumors. Hence, the objective of this study was to evaluate this delivery system in vitro in human ovarian SKOV-3 cells and in vivo in mice with intraperitoneal implants of drug-free or 14C-PTX-chitosan-ePC films. In vitro, 14C-PTX-chitosan-ePC implants (10 mg) provided zero-order constant release of 0.92+/-0.03 pg/day PTX over 5 days. Released PTX retained dose-dependent activity; effectively inhibiting SKOV-3 proliferation with an ED50 of 211 ng/ml of released PTX. Drug-free implants did not affect cell viability or cell morphology of SKOV-3 cells. A sustained, zero-order release of PTX was also seen in vivo over a 2 week period in mice implanted with 14C-PTX-chitosan-ePC films. Correlations between the in vitro and in vivo release of PTX was highly significant (R2 = 0.975). After 2-4 weeks, mice with chitosan-ePC implants did not demonstrate any signs of encapsulation, inflammation or infection. Overall, our in vitro and in vivo results demonstrated zero-order drug release and biocompatibility of the novel chitosan-ePC film. This indicates potential usefulness of chitosan-ePC implants in the sustained and local delivery of anti-neoplastic agents.