Chitosan-xanthan gum microparticle-based oral tablet for colon-targeted and sustained delivery of quercetin

Context: Quercetin (QUE) is a flavonoid with antioxidant/anti-inflammatory properties, poorly absorbed when orally administered. Objectives: To prepare chitosan/xanthan gum microparticles to increase QUE oral bioavailability and optimize its release in the colon. Materials and methods: Chitosan/xanthan gum hydrogel embedding QUE was spray-dried to obtain microparticles characterized by size, scanning electron microscopy, differential scanning calorimetry and X-ray diffraction. Microparticles were compressed into tablets, coated with Eudragit (R) to further prevent degradation in acidic pH. The swelling degree and QUE release in simulated gastric and intestinal pH were investigated. Results: Microparticles were smooth and spherical, around 5 mu m, with successful QUE loading. Microparticle tablets provided resistance to acidic conditions, allowing complete drug release in alkaline pH, mimicking colonic environment. The release was controlled by non-Fickian diffusion of the dissolved drug out of the swollen polymeric tablet. Discussion and conclusion: Microparticle tablets represent a promising dosage form for QUE delivery to the colon in the oral therapy of inflammatory-based disorders.