DESIGN, DEVELOPMENT AND CHARACTERIZATION OF COLON-SPECIFIC MICROSPHERES CONTAINING VONOPRAZAN FUMARATE

Abstract

The present study was aimed at the design, development, and characterization of colon-specific microspheres
containing Vonoprazan fumarate for targeted drug delivery to the colon. Chitosan microspheres were
prepared by the ionotropic gelation method using sodium tripolyphosphate (STPP) as a cross-linking agent.
Six formulations (F1–F6) were developed by varying the concentrations of chitosan and STPP while
maintaining a constant drug concentration. The prepared microspheres were evaluated for flow properties,
percentage yield, drug entrapment efficiency, particle size, zeta potential, in-vitro drug release, release
kinetics, and stability. The flow property studies revealed acceptable micromeritic characteristics for all
formulations. The percentage yield ranged from 70.32 ± 0.45% to 82.25 ± 0.25%, while drug entrapment
efficiency ranged from 68.15 ± 0.65% to 79.32 ± 0.74%. Formulation F5 exhibited the highest percentage
yield and entrapment efficiency and was selected as the optimized formulation. Particle size and zeta
potential analyses of F5 confirmed the formation of stable microspheres with suitable characteristics for
controlled drug delivery. To achieve colon-specific targeting, the optimized microspheres were coated with
Eudragit S100. In-vitro drug release studies demonstrated minimal drug release in simulated gastric fluid and
enhanced release in colonic pH conditions. The coated microspheres released only 0.69% drug in acidic
medium after 1 hour, while 93.32% cumulative drug release was achieved after 12 hours at colonic pH. Drug
release kinetic analysis indicated that the release mechanism followed the Korsmeyer–Peppas model with an
R² value of 0.9341, suggesting non-Fickian diffusion. Stability studies conducted for three months showed no
significant changes in particle size, entrapment efficiency, or physical appearance under refrigerated
conditions. The findings of the present investigation indicate that Eudragit S100-coated chitosan
microspheres of Vonoprazan fumarate can serve as a promising colon-targeted drug delivery system with
controlled release characteristics, enhanced stability, and potential therapeutic benefits.