Development and evaluation of colon-specific releasing nanoemulsion/hydrogel pellets of camptothecin

Abstract

Camptothecin-loaded nanoemulsion (CPT/NE), sodium alginate, carbomer and calcium chloride were chosen to prepare camptothecin-loaded nanoemulsion / hydrogel (CPT/NE/HG) pellets. The optimal formulation of CPT/NE/HG pellets was composed of a mixture of the CPT/NE to hydrogel (1:1, w/w) followed by solidification with 15.0% CaCl2 solution, and the hydrogel consisted of a mass ratio of 1:1 of sodium alginate (1.92 %, w/v) and carbomer 934P (2.20 %, w/v). The reconstitution of pellets showed that there were nanoemulsions, microemulsions or mixed micelles existed together in simulated colonic fluid (SCF). The camptothecin releasing from the CPT/NE/HG pellets was less than 20 % in simulated gastric fluid while more than 40% loaded camptothecin released in SCF, and the release process was conformed to be first-order kinetics. The in vivo imaging indicated that the CPT/NE/HG pellets were firstly aggregated in the stomach while the most pellets were destructed after reaching the colon. The inhibitory effect of CPT/NE/HG pellets on LoVo cell growth was significantly stronger than that of CPT solution.