Characterization of enteric-coated capsules filled with colchicine loaded zein nanoparticles for colon delivery.

Aim: In this study, we developed a dual pH and time-dependent formulation for targeted colonic release, aiming at minimizing adverse effect and enhancing anticancer efficacy of colchicine in the treatment of colorectal cancer.

Materials and methods: To achieve this, colchicine was loaded in zein nanoparticles (Col-Z NP) which were further optimized and encapsulated in Eudragit S100 coated capsules. A full factorial design was employed to determine the optimal condition for preparation of Col-Z NP.

Results: The optimized Col-Z NPs exhibited a spherical shape with particle size of 104.3 ± 1.6 nm, polydispersity index of 0.27 ± 0.01, zeta potential of 29.0 ± 0.1 mV, encapsulation efficiency of 59.8 ± 4.8%, release efficiency over 8 h of 45.5 ± 2.7%, and drug loading of 13.0 ± 0.0%. No notable difference in cytotoxicity was observed between free colchicine and Col-Z NPs at comparable concentrations. The cellular uptake study showed more uptake for coumarin 6 loaded Z NPs compared to free coumarin 6. Colchicine release from coated capsules was restricted to around 3% in gastric medium and increased to about 8% in simulated intestine medium, respectively.

Conclusion: Results suggest that Eudragit S100 coated capsules containing Col-Z NP could be effective delivery system for colchicine to target colorectal tumors.