Fabrication and optimization of itraconazole-loaded zein-based nanoparticles in coated capsules as a promising colon-targeting approach pursuing opportunistic fungal infections

Abstract

Itraconazole (ITZ), a broad-spectrum antifungal drug, was formulated into colon-targeting system aiming to treat opportunistic colonic fungal infections that commonly infect chronic inflammatory bowel diseases (IBD) patients due to immunosuppressive therapy. Antisolvent precipitation technique was employed to formulate ITZ-loaded zein nanoparticles (ITZ-ZNPs) using various zein: drug and aqueous:organic phase ratios. Central composite face-centered design (CCFD) was used for statistical analysis and optimization. The optimized formulation was composed of 5.5:1 zein:drug ratio and 9.5:1 aqueous:organic phase ratio with its observed particle size, polydispersity index, zeta potential, and entrapment efficiency of 208 ± 4.29 nm, 0.35 ± 0.04, 35.7 ± 1.65 mV, and 66.78 ± 3.89%, respectively. ITZ-ZNPs were imaged by TEM that revealed spherical core-shell structure, and DSC proved ITZ transformation from crystalline to amorphous form. FT-IR showed coupling of zein NH group with ITZ carbonyl group without affecting ITZ antifungal activity as confirmed by antifungal activity test that showed enhanced activity of ITZ-ZNPs over the pure drug. Histopathological examination and cytotoxicity tests ensured biosafety and tolerance of ITZ-ZNPs to the colon tissue. The optimized formulation was then loaded into Eudragit S100-coated capsules and both in vitro release and in vivo X-ray imaging confirmed the success of such coated capsules in protecting ITZ from the release in stomach and intestine while targeting ITZ to the colon. The study proved that ITZ-ZNPs is promising and safe nanoparticulate system that can protect ITZ throughout the GIT and targeting its release to the colon with effectual focused local action for the treatment of colon fungal infections.

Keywords: Central composite face-centered design (CCFD); Colon fungal infections; Colon targeting; Itraconazole; Zein nanoparticles.

Fig. 1

3-D Response surface plots showing the effects of the continuous independent variables; A: zein:drug ratio and B: aqueous:organic ratio on, PS (a), PDI (b), ZP (c), and EE% (d)

Fig. 2

DSC thermograms of pure ITZ (a), zein (b), ITZ-zein physical mixture (c), and ITZ-ZNP-optimized formula (d). The curves have been displaced vertically for better visualization

Fig. 3

XRD diffractograms of pure ITZ (a), zein (b), ITZ-zein physical mixture (c), and ITZ-ZNP optimized formulation (d). The curves have been displaced vertically for better visualization

Fig. 4

FT-IR of pure ITZ (a), zein (b), ITZ-zein physical mixture (c), and ITZ-ZNP optimized formula (d)

Fig. 5

release profile of the optimized ITZ-ZNP formulation compared to pure ITZ suspension in phosphate buffer (pH = 7.4) at 37 ± 0.5 °C. Each point represents mean ± SD (n = 3)

Fig. 6

Transmission electron micrographs of a ITZ-ZNPs with magnification power of 50,000 × . b ITZ-free ZNPs with a magnification power of 80,000 × . c Size of ITZ-ZNPs with magnification power 80,000 × , core (red arrows) shell (black arrows)

Fig. 7

Photomicrograph of rabbit colon mucosa after treatment with optimized ITZ-ZNP formulation (a), saline (negative control) (b), and DMSO (positive control) (c)

Fig. 8

Effects of ITZ, ITZ-ZNPs and drug-free ZNPs on the viability of HT-29 cells at 72 h after exposure, P < 0.05. Each point represents mean ± SD (n = 3)

Fig. 9

In vitro drug release of ITZ from the optimized ITZ-ZNP-loaded colon-targeted capsules compared to the release from pure ITZ-loaded colon-targeted capsules, in simulated gastric pH (2 h), simulated intestinal pH (3 h), then simulated colon pH (19 h) at 50 rpm and a temperature of 37 ± 0.5 °C. Each point represents mean ± SD (n = 3)

Fig. 10

X-ray imaging of BaSO₂-ZNPs-loaded colon-targeting capsules after oral administration in human volunteers. a 0.5 h post-dose, b 3 h post-dose, and c 5 h post-dose