pH-RESPONSIVE EUDRAGIT® S-100 COATED CHITOSAN NANOPARTICLES FOR TARGETED CURCUMIN DELIVERY IN ULCERATIVE COLITIS: FORMULATION AND OPTIMIZATION

Objective: This study aimed to develop and optimize pH-responsive Eudragit S-100 coated chitosan Nanoparticles (NPs) for targeted curcumin delivery in Ulcerative Colitis (UC). The objectives included enhancing curcumin's bioavailability, achieving colon-specific release through mucoadhesive, pH-sensitive nanocarriers, and evaluating their long-term stability. Methods: Curcumin-loaded chitosan NPs were prepared via ionotropic gelation using Sodium Tripolyphosphate (STPP) and coated with Eudragit S-100 via solvent evaporation. Nine formulations (F1–F9) were optimized by varying chitosan (250–750 mg) and STPP (500–1000 mg) concentrations. The NPs were characterized for particle size, zeta potential, Entrapment Efficiency (EE), morphology (SEM), and in vitro drug release in simulated gastrointestinal pH (1.2 → 7.5). Release kinetics were analyzed using Zero-Order, Higuchi, and Korsmeyer-Peppas models. Stability studies were conducted at 4 °C, 28 °C/65% RH, and 40 °C/75% RH for 90 days to assess particle size and drug retention. Results: The optimized formulation (F4: 500 mg chitosan, 500 mg STPP) exhibited a mean particle size of 355.5 nm, high EE (76.65%), and a zeta potential of −36.32 mV, confirming colloidal stability. Coated NPs demonstrated pH-dependent release: minimal in acidic pH (2.32% at pH 1.2) and sustained in colonic pH (98.33% at pH 7.5). Release kinetics followed the Korsmeyer-Peppas model (R² = 0.9892, n = 0.62), indicating anomalous transport. Stability studies revealed excellent retention of particle size (≤361.4 nm) and drug content (>99%) under varied storage conditions, confirming long-term stability. Conclusion: Eudragit S-100 coated chitosan NPs successfully addressed curcumin's solubility and bioavailability challenges while ensuring pH-responsive, targeted colonic delivery. The optimized formulation (F4) exhibited robust stability, making it a promising candidate for UC therapy. Future studies should focus on in vivo efficacy and clinical translation.