A novel submicron emulsion system loaded with vincristine–oleic acid ion-pair complex with improved anticancer effect: in vitro and in vivo studies

BACKGROUND: Vincristine (VCR), which is a widely used antineoplastic drug, was integrated with a submicron-emulsion drug-delivery system to enhance the anticancer effect. METHODS: After the formation of a VCR-oleic acid ion-pair complex (VCR-OA), the VCR-OA-loaded submicron emulsion (VCR-OA-SME), prepared by classical high-pressure homogenization, was characterized and its in vitro anticancer effects were evaluated. RESULTS: The submicron-emulsion formulation exhibited a homogeneous round shape. The mean particle size, zeta potential, and encapsulation efficiency were 157.6 ± 12.6 nm, -26.5 ± 5.0 mV and 78.64% ± 3.44%, respectively. An in vitro release study of the VCR-OA-SME revealed that 12.4% of the VCR was released within the first 2 hours (initial burst-release phase) and the rest of the drug was detected in the subsequent sustained-release phase. Compared with VCR solution, the pharmacokinetic study of VCR-OA-SME showed relatively longer mean residence time (mean residence time [0-∞] increased from 187.19 to 227.56 minutes), higher maximum concentration (from 252.13 ng/mL to 533.34 ng/mL), and greater area under the curve (area under the curve [0-∞] from 11,417.77 μg/L/minute to 17,164.34 μg/L/minute. Moreover, the VCR-OA-SME exhibited higher cytotoxicity (P < 0.05) on tumor cells by inducing cell arrest in the G2/M phase or even apoptosis (P < 0.05). CONCLUSION: The VCR-OA-SME formulation in our study displayed great potential for an anticancer effect for VCR.